The Wonders That Lie Within Our Milky Way Galaxy | Cosmic Vistas S4 Compilation | Spark

A foreign misty light spreads across the shimmering vault of the heavens. At first it looks like a cloud or a cloud of smoke that might blow away in a strong breeze, but it stays in place among the stars because it is something more permanent and more intriguing. More than a passing cloud, this is what the Romans once called the via latia, the Milky Way, and for astronomers throughout the ages it has proven to be a path to discovery. For ancient sky watchers, the Milky Way was a mystery that became a myth, some saw it as the wake of a celestial ship, others as the seam where the two halves of the sky met, but these stories and legends tell more about the people who told them than about the true nature of the Milky Way to the ancient Greeks.

The path was formed when the goddess Hera woke up and she found a strange baby, baby Hercules, suckling at her breast. The divine milk granted her immortality, but when Hera realized that she had been deceived, she pushed the Baby and the milk that she dripped spread across the sky today our word. Galaxy comes from the Greek word for milk, but stories aside, the true nature of the Milky Way was hidden until people could see it through a telescope. It was 1609 when Galileo first pointed the new invention into the hazy light of the Milky Way and recorded what he saw Galileo had discovered.

That the Milky Way is made up of countless stars, stars that are too far away and too faint to see individually, but together they paint the sky with a luminous glow, was a realization that changed everything because it gave depth to the night sky and meant to astronomers . Galileo noticed that stars in the Milky Way sometimes grouped together in clusters, and as telescopes improved, astronomers discovered something else: clouds of bright gases called nebulae that they would later turn out to be the birthplaces. of stars, many of them located throughout the Milky Way like gems in a

cosmic

necklace, but even when the telescope discovered the Hidden Treasures within the Milky Way, it left one big question unanswered: why is the Milky Way confined to a narrow band that surrounds it? heaven would pass another century and a half after Galileo before anyone had the first hints of an answer in 1785 William Herschel, a German-born musician and astronomer working in England, already famous for his discovery of Uranus, was the first planet of the solar system. system to be detected with a telescope Now Herschel was ready to focus his attention on the location of stars around the sky, including the Milky Way.

His strategy was simple but thorough by pointing his telescope at more than 600 different locations. Herschel proceeded to count all the stars he saw in each region and estimated the relative brightness of each star. Herschel assumed that the fainter stars were farther away than the brighter stars, so when he put it all together he got a picture of the universe that looked like this: It shows that we are embedded in a vast star system that has a flattened shape like a rock. like a giant windmill or a disk in some directions, the stars are relatively few in number, but along the median plane of the disk the stars become more numerous and their light adds up to form the bright band of The map of the Milky Way Herschel's work was a huge step forward, but it was also just the tip of the

cosmic

iceberg, for beyond the limits of Herschel's telescope, a much grander Milky Way still awaited discovery based on the work of William Herschel's astronomers. in the XIX century.

The 19th century had verified that our solar system is located within a giant disk-shaped

galaxy

of stars, which explains why the Milky Way appears to us as a bright band of light stretching across the sky when we look into the sky. throughout the band we are looking towards the album. But astronomers were not entirely satisfied with this early image of our

galaxy

because it meant that the solar system had to be located near the center of the Milky Way (an unlikely coincidence) and without a way to measure the true distances to the stars they could not There was a way to find out how accurate this image of the Galaxy could be to gain a deeper understanding of the Milky Way astronomers needed new tools and new ideas in 1912 they had the new idea was a way to directly measure distance in space profound and her discovery was totally unexpected in the pre-electronic era Henrietta Levitt was one of several women employed by the Harvard University Observatory to do mathematical calculations.

At that time, large amounts of data were flooding the observatory thanks to the development of astronomical photography. The female computers who worked at Harvard. They weren't expected to make their own scientific discoveries, but that's precisely what happened when Levitt noticed a pattern in a certain type of variable star called a Cepheid variable star. Levitt saw that each Cepheid pulsed with a regular cycle and that the length of the cycle was related to the total amount of light coming from the star. By simply timing the pulsations of a Cepheid variable, astronomers could now calculate the true brightness of the star and then Calculating its distance by comparing it to how bright it appeared in the sky, the method was quickly put to use with the help of the most powerful astronomical telescope of the time, the 60-inch reflector atop the summit of Mount Wilson, near Los Angeles, backed by the unprecedented power of the telescope, Harlow Shapley, a crime reporter turned professional astronomer, would make galactic history, precisely used the giant telescope to examine. globular clusters distant concentrations of stars with a clearly spherical shape each globular cluster contains hundreds of thousands or even millions of stars that revolve around each other like bees in a swarm Shapley believed that these clusters in turn must revolve around the gravitational center of the Milky Way Using Cepheid variables to measure distances to the Clusters, Shapley was able to determine the location of a point in space around which all the Clusters appear to be concentrated.

The result changed everything and showed that the real center of the Milky Way is located tens of thousands of light years away from us, in the direction of the constellation of Sagittarius. For astronomers, the Revelation was a cosmic wake-up call, centuries before, It was Nicholas Copernicus who had pushed the Earth away from the center of the solar system and now placed the Sun there. It was Shapley's turn to move the solar system away from the center of the Milky Way. Shapley's Discovery relegated us to the suburbs of a galaxy that is much larger than anyone had imagined.

Today astronomers estimate that the Milky Way is more than one hundred thousand light years long. However, even in Shapley's time there was growing evidence that this vastly expanded Milky Way was only a small part of a much larger cosmic reality. That evidence came in the form of a class of faint, diffuse objects scattered across the sky that were appearing. As telescopes improved, many looked like small spindles, others had a distinctly spiral shape. It seemed to some that these faint eddies must be newborn solar systems forming within the Milky Way, but there was also a more radical possibility that they could be other galaxies like the Milky Way.

But in the early 1920s, astronomer Edwin Hubble, far into cosmic distance, was able to show that the answer was yes. Using the newly built 100-inch telescope on Mount Wilson, Hubble zoomed in on the largest of the mysterious spirals, the Great Andromeda Nebula. There he discovered Cepheid variables, the pulsating stars that would again prove crucial, this time allowing Hubble to calculate the true distance to Andromeda. The results would become a turning point in our understanding of the cosmos. Hubble measurements showed that Andromeda must be a separate galaxy far beyond. The boundaries of the Milky Way today astronomers have set its distance at more than 2 million light years away.

Other galaxies are millions and even billions of light years further away. Hubble had discovered the rest of the universe, but he had also given astronomers a new way of thinking. the Milky Way compared to other galaxies the era of galactic exploration was about to begin in the mid-1920s astronomers had realized that the universe is full of galaxies like islands in a cosmic sea galaxies are separate systems , each containing hundreds of billions of stars, but this Revelation raised many new questions about our own galaxy. The Milky Way was a spiral system like some of the others that could be seen from afar, and if so, how would we know that it had taken astronomers centuries to discover that the Milky Way?

The Milky Way is shaped like a large disk with the solar system located about two-thirds of the way from the center. Now the challenge was to map the Milky Way from the inside. This was no easy task and a big part of the problem is even old dust. Astronomers were able to see that the Milky Way does not have a uniform appearance in the sky, but rather looks irregular and uneven in places, it seems divided by dark fissures. This is because the Milky Way is interwoven with vast clouds of interstellar dust that block out much of the Galaxy.

From our view, despite this visual barrier, there are clues that helped astronomers discern the true shape of our galaxy. One of the first to follow these clues was the American astronomer William Morgan in 1951. Morgan worked at the Yerkes Observatory northwest of Chicago, where he studied blue supergiant stars. One night, while looking in the direction of the constellation Perseus, Morgan noticed that several of the giant stars he had been studying in that part of the sky were located approximately the same distance away, between five and eight thousand. light years away and so is the Perseus double star cluster, a well-known feature in the same part of the sky.

Morgan realized that the double cluster and giant stars together drew a line through space as if marking a structure embedded within the Milky Way. He had discovered the Perseus Arm, one of the great spiral arms of our galaxy, and soon after other familiar sites scattered throughout the Milky Way were shown to be part of the Perseus Arm, including the spectacular Crab Nebula. , the remnant of a supernova explosion that was recorded in 1054. But if there was one spiral arm there should also be others. When looking in the opposite direction from Perseus, astronomers discovered that they could see traces of another arm lying closer From the center of the galaxy, this is the Sagittarius Arm.

A dazzling array of star clusters and nebulae adorn the southern Milky Way. Spectacular sights like the Trifid Nebula make this part of the sky a visual paradise closer to home. Astronomers have determined that our own solar system is part of the Orion Arm, a smaller structure that may be nothing more than a spur branching off into Sagittarius, yet the Orion Arm 2 is loaded with jaw-dropping views that charge great importance in our view because they are relatively close. When we look down along the Orion Arm, we see the closest and most spectacular star-forming region in the sky, the Great Orion Nebula, where thousands of new stars are being born before our eyes with the help of radio telescopes and infrared satellites.

They can see through the dust obscuring the galaxy. Astronomers have now looked deep into the Milky Way to map its structure in detail. They have detected more arms and have also confirmed that the Milky Way is not just a spiral galaxy but a barred spiral. Barred spiral galaxies are common in the universe. Its elegant appearance is the product of an evolutionary process. which causes material within the galaxy to form a horizontal bar running through the center Now, more than 60 years after Morgan's initial discovery of the Perseus arm, astronomers can show us what the Milky Way would look like if we could see it from the outside.

The result is an artistic view that shows our galaxy as a barred spiral with two prominent arms, one of them is the Perseus arm, the first to be mapped on the opposite side is the Centaurus scutum arm, it is much more difficult to distinguish from Earth, but astronomers have discovered that it hosts massive clusters of young, hot stars like this one, imaged in infrared light by the Spitzer Space Telescope. Completing the view are the smaller spiral arms that wind their way between the two larger ones, including the arm where our own is located.solar system right here.

It's a view no telescope can show us, but it's backed by years of observing across the Milky Way. Mapping our galaxy is one of the great achievements of astronomy, but it is more than just a map: it is a snapshot of a dynamic star system with a history that has unfolded over billions of years, a history that It is directly related to our own existence. This is the symbol of life. Because of its spiral galaxies, new stars and new planets are born. It is the same process that led to the creation of our own solar system in the Milky Way.

In that sense, the spiral can Being the ultimate cosmic symbol of life because in its spiral galaxies new stars and new planets are born and, sometimes, civilizations like ours with the desire to map and explore the universe that surrounds them, it is so strange. experience there are few places as inspiring as a dark sky full of stars throughout history our night vision of the universe has fueled our collective imagination it has helped give rise to great works of art and profound knowledge, but when it comes to the birth of the universe not even the most creative work of imagination can rival the history that science has now revealed.

It is a story that begins with an explosion. Welcome to the Big Bang, the energetic burst at the beginning of cosmic history that triggered the expansion of space and the creation of all matter. is our definitive beginning the discovery that there was such a beginning is one of the characteristic triumphs of 20th century science now the challenge of understanding it is underway every great civilization in history has its creation History the explanation that answers the question how Did all this come about? In some ways, the Big Bang theory has a lot in common with those stories because, like them, it evokes a vision of supreme forces and amazing events beyond.

Human experience, the difference is that the Big Bang story is supported by evidence that we can find around us if we know how to look. This is Europe's Planck satellite, a time traveler orbiting back in time dating back more than 13.5 billion. years to bring us to the threshold of the Big Bang Planck has given us the most comprehensive view yet of a crucial turning point when light was first able to move freely through space and carry with it information about how the universe began to achieve this vision. Planck has explored the depths of space in all directions creating a map of the entire sky, but what that map shows is not a familiar scene of stars and galaxies, but a faint signal emanating from the darkness beyond the cosmic background that lies behind. lies behind everything else.

It is a direct view of the universe when it was only 380,000 years old, just a small fraction of its current age. At first glance, these few might seem impossible because it suggests that we may be witnessing something that took place before the Earth existed. but in fact we can, thanks to the finite speed of light, light is the fastest thing we know in nature. It travels through space at almost three hundred thousand kilometers per second. At that speed, the light we see from the Moon takes only 1.3 seconds. to reach Earth That's incredibly fast, but it still means that when we look at the Moon we're looking into the past, a path that took place on the lunar surface 1.3 seconds ago.

The planet Saturn is much further away than the Moon, so its light takes longer to reach us. Yes. When we look at Saturn's rings through a telescope, we are also looking more than an hour back in time, looking beyond our solar system, the difference between the past and the present becomes truly dramatic. Here are the Pleiades from a bright star cluster located about 400 light years away. It means that when we see the Pleiades we don't see them as they are now but as they were 400 years ago, when Galileo was recording his first view of the Pleiades through a telescope, but our ability to time travel becomes truly impressive once we we appear beyond. the limits of our own galaxy, the Milky Way, here is the Andromeda galaxy, the most distant object visible to the naked eye, it is located more than two and a half million light years away, so our view of Andromeda in It actually shows what this galaxy looked like two and a half years ago. millions of years ago, long before the first Homo sapiens walked the Earth, such a span of time is incomprehensible on a human scale on a cosmic scale it is a small step exploring deeper into space with powerful telescopes we see countless galaxies that are tens or hundreds of millions At a distance of light years today, as we approach the farthest extremes of visibility, we can make out light from galaxies that are 12 billion light years away.

Seeing them means we can see more than 90 percent of the way back to the Big Bang. At this point there are no more galaxies to observe because at such a remote and early time galaxies had not yet formed, but we can still look further, towards a time when light did not come from stars or galaxies, but from the glowing fog of hot gas that filled the Earth. universe after the Big Bang this is where the Planck satellite took us and it is here where we can find the clues that will lead us to a deeper understanding of the Big Bang 13.5 billion years ago our universe looked very different than it does today , this is a time just a few hundred thousand years after the Big Bang, when space was filled with particles still too energetic to form atoms.

Today, that early stage of cosmic history is imprinted in the heavens revealed in this detailed Planck map. To the satellite eye, the map appears to lack any strange apparent pattern, but when analyzed mathematically, these colorful specks provide a detailed measurement of the basic properties of the universe and a window into the Big Bang itself. The key to understanding the map is to realize that it is a temperature record that shows us a universe that has been cooling since its fiery infancy. Red represents distant regions of space that were slightly warmer than average in the distant past, while blue is for those regions that were slightly colder.

These differences are like the cosmic seeds that allowed matter to accumulate in some areas of space while leaving others practically empty, today the vast clusters of galaxies that we see around us are byproducts of this primordial accumulation of matter, but if Planck can look back to a time when all of space was filled with a hot gas then why doesn't the sky look white now the answer to that question challenges one of our deepest intuitions about the universe the idea that it always has been here in ancient times, looking at the sky was like coming face to face with eternity.

Perhaps that is because here on Earth time brings growth and decay while above the stars appears the eternal Aristotle, the most influential of ancient thinkers, thought he had demonstrated that the universe was eternal to him the notion that there could be nothing before there was something offended. reason itself, but when Isaac Newton discovered his law of gravity a problem soon arose with eternity because gravity, all stars must be attracted to each other, but if the universe is eternal, why haven't the stars already converged on each other? One place? That question lingered uncomfortably for more than two centuries until the 1920s, there was a new theory of gravity thanks to Albert Einstein, and astronomers had realized that stars are grouped into galaxies and that galaxies are scattered throughout space but The problem of Eternity remained in an endless span.

For a long time, gravity should have united all galaxies to avoid this contradiction. Einstein changed his equations in a way that exactly counteracted the influence of gravity on space, but Einstein soon discovered that he need not have bothered in 1929, following earlier work. by other astronomers Edwin Hubble announced that most galaxies are moving away from ours. He discovered it by spreading the light from each galaxy into a spectrum like a rainbow. Anything that moves away will appear to emit light that has shifted toward the red end. of the spectrum that is exactly what Hubble saw and the further away a galaxy was, the faster it seemed to recede to Hubble and for scientists since then the most logical explanation is that space itself is expanding and dragging galaxies with it in a being. human.

At scale, the expansion of the universe is happening too slowly for us to realize that with each meter of space growing only the diameter of one atom every 10 years, that's not enough to overcome the gravity that holds the stars together, so that the Milky Way is not enough. It's not getting bigger and we're not strangers either, but in the great void between galaxies the expansion of space is adding up and it means that, in general, galaxies are moving apart rapidly, it also means that if we travel back in time, The galaxies we observe today were once much closer together than they are now, thanks, and at some point in the past there would have been no distinct stars or galaxies, just a continuous glow of hot matter.

This is the universe seen by the Planck satellite, but today in space. has expanded so much that the light from this initial period has redshifted beyond the reach of the human eye beyond the infrared to eventually become a signal in the microwave part of the spectrum. That signal was discovered by accident in 1964 when Robert Wilson and Arno Penzius, two radio astronomers from Bell Laboratories, pointed an antenna toward the sky and could not understand why the entire sky was emitting microwaves. Without realizing it, they had discovered the cosmic background, proof that the universe as we know it is not eternal but had a definite beginning.

In time there was a big bang, but there was more to come as the space age flourished, and so did the realization that this message from the distant past held the key of our cosmic origins. The Big Bang theory tells us that the universe we see today was born from a hot mixture of particles that would eventually cool to form atoms, stars, and galaxies, but because the universe is expanding, that bright beginning has faded from view. view. Fortunately, it can still be found in the form of a cosmic background of microwave energy coming from every direction in space and space is the best place to see it 9.

NASA launched Kobe, the Cosmic Background Explorer, its mission was not only detecting the cosmic background but seeing if it could reveal important details about how the universe evolved was not an easy task, previous studies with high-altitude aircraft had already shown that the cosmic background is remarkably uniform throughout the sky, but somehow that The uniform glow of the distant past had given way to the very diverse Universe in which we now live, a universe containing large congregations of surrounded galaxies. by huge voids of empty space, so when Kobe began mapping the entire cosmic background, scientists looked for subtle differences hidden in the smoothness of the ancient universe, what they discovered was a remarkable confirmation of the Big Bang.

In this image of Kobe, the cosmic background appears smudged. Very slight differences in temperature on the order of 100,000 degrees, scientists were ecstatic, although these variations were minuscule, they meant that Kobe was seeing the first hints of large-scale structure in the universe, it also meant that the cosmic background could serve as A link to an even more distant past, scientists realized that the spots were traces of momentary energy fluctuations that occurred when the universe was just a fraction of a second old, but a space expanded rapidly, those small fluctuations stretched until Reaching a giant size and finally making their mark on the cosmic microwave background Kobe had revealed the power of the cosmic background as a window to the Big Bang now scientists were eager to learn more killing Kobe's success NASA began work on the probe Wilkinson Microwave Anisotropy Test, wmap for short, which was launched in June 2001.

Like Kobe, wmap was designed to image the entire cosmic background, but it would do so in much greater detail. The surprising result would challenge theories about how the big bang unfolded abroad. On the one hand, wmap confirmed that much of the mass of the universe is in the form of invisible Dark Matter consisting of undiscovered particles that are heavier than those that make up stars and galaxies. Wmap brought us a big step closer to understanding the Big Bang, but the plonk mission would go even further. Planck was built to study the cosmic background at more wavelengths and with even greater precision than Wmath, after more than 15 months of scanning, scientists began carefully removing thelayers in the ultrasensitive Planck chamber.

The first microwave sources that are close in space had to be subtracted from the image below. Scientists removed all energy coming from distant sources within the plane of the Milky Way and from the wispy dust clouds that are ubiquitous throughout our galaxy. Finally, what was left was the cosmic background seen like never before. The result was a triumph when he was released. In March 2013 it became clear that the new map offered a remarkable portrait of the universe in concrete numbers. Among those figures is the precise age of the universe, which Planck measures at 13.819 million years. It also provided a detailed breakdown of how the map content works.

The universe is divided between ordinary matter, including stars and galaxies, dark matter that does not emit light but accounts for most of the mass of the universe, and a third ingredient called dark energy that is causing the expansion of space to accelerate over time. These numbers are crucial. Because they can help cosmologists distinguish between different variants of the Big Bang theory, the dominant idea about how the universe came to be is called inflation. It proposes that in the first billionth billionth billionth of a second after the big bang, the universe expanded exponentially driven by a release of energy from the vacuum of outer space, among other things inflation explains why the universe looks so similar throughout of great distances in all directions.

Scientists working with Planck say he dismisses some versions of inflation but is consistent with others; However, there are also alternative ideas. including some who say that the universe we know today is part of a repeating cosmic cycle, so there may be other universes before this one To help distinguish between these possibilities, scientists are now looking for signs that the gravitational waves produced by the Big Bang left their mark. Regarding the cosmic background, perhaps the most important result of the Planck mission is that on many scales the cosmic background appears mathematically simple. This in itself may be telling us something profoundly profound about the cosmos.

A universe that began with an explosion but has evolved into a symphony of shapes and phenomena a universe that may have started simple but has become a truly inspiring place years at a distance of 150 million kilometers from Earth the Sun is all the star we need. Its energy stirs up our atmosphere, keeps our oceans liquid and makes life possible, but imagine if the sun were more than three times bigger in our sky and exploded every exposed surface with up to 10 times more energy, then the Earth would be a very different world, a world governed by heat and light, a world like Mercury with its baked surface. and the battered surface Mercury looks like a no man's land among planets, but it is a no man's land that scientists need to explore since the planet closest to the Sun Mercury lives in a cosmic Hot Zone that contains important clues about the origins of our system solar and may be our key to understanding conditions on countless alien worlds scattered across the Galaxy for centuries Mercury eluded astronomers' best efforts to learn its secrets the reason boils down to geometry as seen from Earth the angle between Mercury and the Sun Never exceeding 30 degrees, the only way to separate the planet from the sun's overwhelming glare is to look very low toward the horizon immediately after sunset or just before sunrise.

Under such conditions, even the world's largest optical telescopes were unable to show any details about Mercury's surface until the dawn of the space age. That all changed with Mariner 10. Launched in 1973, this Intrepid spacecraft was designed to fly by Venus, but scientists realized they could get two planets for the price of one if they included Mercury as a second target. During 1974 and 1975, Mariner 10 made three separate Mercury passes approaching 327 kilometers. of the planet's surface during its third and final approach during those historic encounters, centuries of speculation were replaced by a stark new image of the innermost world of the Solar System.

Mariner 10 revealed a cratered planet that looked a lot like Earth's Moon, most of the craters dating back billions of years because Mercury is too small and too hot to retain a thick atmosphere, its surface It does not experience erosion by water or wind, yet hidden in this ancient surface are tantalizing signs that Mercury has changed over the eons and that, despite its outward appearance, Mercury is very different from our Moon. Inside, one clue is the planet's surprisingly large mass. Mariner 10 discovered that Mercury is almost five times more massive than the Moon, although its diameter is only 40 percent larger for it to be so heavy.

Mercury must hide a huge metallic core covered by a relatively thin skin of lighter rock. This idea was further reinforced by Mariner 10's discovery that Mercury has a magnetic field, although it is much weaker than Earth's. The presence of the field suggests that at least part of Mercury's core is still in a molten State Mariner 10 attempted to get more clues from its survey of Mercury, but during its three brief passes the spacecraft imaged less than half of the surface. of the planet and what he found left many questions unanswered. Another mission to Mercury was clearly needed, one designed to stay much longer.

The dream of returning would remain unfulfilled for almost 30 years. Finally, on August 3, 2004, NASA's messenger spacecraft set out to become the first planetary probe. to orbit Mercury and reveal its features and characteristics in detail, but just getting there would be half of the challenge Mercury is much closer to Earth than most other planets in our solar system, but it also lies deep within the gravitational field from the Sun, causing it to travel through space at a drastically different speed, about 65,000 kilometers per hour faster than Earth in To get into orbit around Mercury instead of simply sailing on a messenger, you would first have to match its speed at that of the planets.

Paradoxically, that meant the spacecraft would have to lose energy to allow it to gradually spiral closer to the Sun. The journey would take over. Six and a half years ago, a foreign messenger passed by Mercury on three separate occasions, giving scientists the opportunity to test the probe's cameras and sensors. The results were spectacular, but the fleeting flashes only weakened scientists' appetite for more data in March 2011. The messenger approached Mercury for the fourth time. and last time, this time moving at just the right speed to be captured by the planet's gravitational pull, the long-awaited exploration of the Solar System's innermost planet was ready to begin thanks to the messenger Mercury was finally having its moment on the Sun.

Elusive and fast moving. In The Twilight Sky, ancient astronomers named the planet Mercury after the messenger of the gods, but it wasn't until 2011 that NASA's own Messenger mission was in a position to reveal one of the least explored worlds in the solar system. Messenger came well equipped for the job. As on Mercury, it is so intense that it would easily burn an unprotected spacecraft, so Messenger is covered with thermal insulation and has a built-in system of radiators that are designed to extract heat from its sensitive electronic components, thirds of the surface of its solar panels. . They are reflected to deflect rather than absorb solar energy and help control temperature.

Finally, the main body of the spacecraft remains hidden from direct sunlight by a large sunshade made of ceramic fabric on a lightweight titanium frame, while the outer surface of the sunshade can reach 370 degrees. Celsius hot enough to melt the lead behind this essential barrier, the spacecraft operates at room temperature, scientists hoped the measurements would be enough for Messenger to survive at least a year in the hostile environment around alien Mercury, but when Messenger began to reveal the complex geology of the planet, they soon realized. Hoping to get more, with a wide- and narrow-angle camera, Messenger could map Mercury's entire surface down to features a kilometer wide and zoom in on areas of special interest to see details as small as 20 meters across.

The camera system could also be used to reveal slight color differences in Mercury's rocky terrain that would otherwise be too subtle for human eyes to discern. This would be useful for reconstructing the multi-layered history exposed by Mercury's craters, and there were many craters to observe on the Moon. There is a long tradition that Mercury's craters are named after scientists and philosophers; Instead, it was decided that the craters should be named after famous artists, composers, and authors, but while all of Mercury's craters may have the arts in common, Messenger soon discovered some surprising differences between them here. messenger Zooms in on two craters Degas and Brontë located next to each other to the human eye, they appear identical in color, but messenger reveals that the dega looks bluish relative to the brownish color of Brontë.

This difference suggests that the surface of Mercury includes layers of rock with different compositions in In this case, the impact has passed through a blue or colored rock underlying the brown. Elsewhere, the color differences are more complex, indicating a rich and diverse geological history that was not evident to scientists before the messenger arrived. Sometimes the effect of an asteroid or comet impact is obvious. Because it scatters material in bright rays across an older set of features, but not all parts of Mercury's surface are formed by an impact from above In this intriguing image, an orange spot stands out against a landscape darker in color seen up close in black and white.

The object in the center of the spot looks like a tall peak inside a crater, but this is no ordinary crater; is the likely scene of a volcanic eruption that spewed orange-colored material from deep inside the planet. He has confirmed that mercury is covered in features. like this one that could only have resulted from volcanic activity here a crater called Faulkner appears half sunken in the landscape the crater was probably flooded by lava that topped its former rim and filled it halfway with molten rock elsewhere the large Rachmaninoff crater presents a double rim with the outer ring measuring more than 30 kilometers wide, color differences show that lava flooded the center of the crater long after its formation and then spilled into the region between the inner and outer ring;

In other cases, the colors on Mercury's surface are more difficult to interpret. For example, the floors of some craters have bright holes that stand out against the darker rock and are completely different from anything seen on the moon. The exact nature of these glowing spots remains a mystery, but scientists suspect they may be the result of some minerals turning gaseous under sunlight. Intense glow One area where Mercury's color is especially telling is the Caloris Basin, 1,500 kilometers in diameter, by far the largest impact feature on the planet. Boris formed in the first billion years of the history of the Solar System when a very large asteroid hit Mercury over time. other smaller craters marked the basin and then lava covered the vast central plain of the basin, leaving the raised edges of the smaller craters jutting out like blue islands.

In contrast, the edge of the giant basin is marked with orange spots where hot lava found a path to the surface. Meanwhile, across the shattered bedrock in the center of the Caloris Basin, the messenger has discovered a strange network of channels that spread like spiders across the Basin's floor. These are indications that the surface of the Basin may have been stretched or stretched in the past with its large size. At the core of the palette there appears to be little doubt now that Mercury was once a geologically active planet and that it remained so long after its formation.

Now, with the help of Messenger's trove of images and data, scientists are gaining a deeper understanding of the hidden forces lying beneath Mercury's pockmarked surface. Light years from Earth, a newly discovered world basks in the fierce light of an alien Sun. This is one of many planets discovered by NASA's Kepler Mission, which was designed to searchworlds like Earth, small and rocky at just the right distance from their stars. to allow for the presence of liquid water, but in the course of its search Kepler has also found many planets that look more like Mercury and orbit much closer to their stars, long ignored by planetary explorers.

Mercury has now become our best reference point for understanding countless other hot planets. The worlds that populate our galaxy by the billions and that are of special interest to scientists are those features of Mercury that are not found anywhere else in the solar system. Features such as towering cliffs that wind through Mercury's battered terrain for hundreds of kilometers. Here one of those cliffs cuts the old crater. Ramo in half, leaving one side of the crater two kilometers higher than the other after having photographed the entire surface of the mercury. NASA's messenger spacecraft has confirmed that cliffs like these are widespread across the planet.

They are now thought to have formed when Mercury's giant metallic core cooled and gradually this left the planet with an outer skin that was too large as the interior became smaller, the surface warping forming cliffs like giant wrinkles in a planetary envelope The cliffs are an example of how Mercury's outer appearance has been shaped by internal forces. Scientists combine messenger data with ground-based radar measurements. The true nature of Mercury's dynamic interior is now coming into focus. A key discovery is that Mercury's metallic core is even larger than expected, making up 85 percent of the planet's total diameter.

The core is likely made of solid iron like Earth's. At least part of the outer core must be liquid. It is the movements within this electrically charged liquid that are responsible for generating Mercury's magnetic field. However, this image presents scientists with a dilemma. If Mercury's core is made only of iron, it should have completely solidified by now, since the smaller the planet, the faster the internal heat escapes, even on a planet. as hot as mercury. This has led researchers to speculate that lighter elements such as silicon and sulfur are present in Mercury's core in significant quantities. quantities that would reduce the melting point of the core and leave the outer portion liquid.

Mercury's liquid core may even be surrounded by a shell of solid iron sulfide, something not seen on any other planet, but while this explanation satisfies all the data, it leads to a larger mystery in explaining why the core Of Mercury is so large, scientists have speculated that Mercury was once again like Earth or Venus, a larger planet with a thick rocky mantle surrounding its core. The collision was another object that detached much of that mantle, leaving the core intact. Another theory suggests that in the early days of the solar system, the Sun went through a much hotter phase and boiled part of Mercury's mantle with its intense heat, but the latest findings challenge both theories.

Instead, Mercury may have formed as it is now small, but rich in lighter elements once thought not to be abundant so close to the Sun. Whatever the explanation, it is clear that there is something to Mercury's history. and in the formation of the solar system as a whole that we still don't understand and that's not the only way Mercury is defying expectations is that here, in a world so completely baked by the Sun, the Messenger has also discovered ice As difficult as this is to imagine that scientists already had indications that there was ice on Mercury because radar observations indicated that there is highly reflective material.

Somewhere near the planet's north and south poles, Mercury's poles are where we find deep craters whose bottoms remain in perpetual darkness as Mercury spins on its axis. They are protected from direct sunlight. These craters are like cold traps for water vapor brought to Mercury by colliding incoming comets. with the planet's surface, although Messenger's cameras cannot see these dark-bottomed craters, Messenger detected the presence of ice with a device called a neutron spectrometer that measures how much the ice absorbs the energy of incoming cosmic rays. Data suggests there could be as many as a trillion. tons of ice on Mercury at a depth of several meters.

If so, the ice constitutes a tempting target for future exploration of the planet's surface. Time and time again, Mercury has proven to be a surprising place, not just a hotter version of our Moon, but a fascinating world in its own right with a history that is crucial to our understanding of rocky planets everywhere, which is why that the European and Japanese space agencies have now joined forces to send another mission to Mercury that is scheduled to arrive early in the next decade once Mercury was the least understood planet today has become one of the most interesting and the ambassador of a vast and emerging population of newly discovered worlds that together form the cosmic Hot Zone so beautiful in the Milky Way that a small particle of matter flies like a bullet.

Through the vacuum of space, propelled by colossal forces, the particle moves at nearly the speed of light, zipping past stars and glowing clouds of gas. Where stars are born, suddenly, a planet appears right in front. Unstoppable, the high energy particle tears through the planet's atmosphere, collides with a nitrogen atom, destroying both particle and atom in a flash of pure energy, now that energy creates new particles that cascade causing more collisions. As they move forward, soon thousands and then millions of more particles spread out in magnification. cone and then collide with the surface of the planet The Earth has just been hit by a cosmic ray during the last century.

Astronomers have devised a multitude of ways to obtain information about the universe. Stars emit visible light but also emit ultraviolet infrared light. Rays and other forms of light that our eyes cannot see. What makes cosmic rays so interesting is that they are not another form of light, they are chunks of matter that come directly to us from deep space. Cosmic rays carry information about powerful forces. and events that take place thousands or even millions of light years away, but to understand what cosmic rays can tell us about the universe, we need to know how they occur.

In fact, it took scientists a while to understand that cosmic rays even exist. Its roots date back to the discovery of radioactivity by French physicist Anri Becquerel in 1896. Radioactivity is particle radiation that comes from atoms that spontaneously break down in the environment. When it was discovered, scientists realized that radioactivity could explain why they could never get an object to stand up. to its static electrical charge indefinitely due to radioactivity in rocks and soil, there are always particles present near the Earth's surface, those particles can interact with anything that has an electrical charge, causing that charge to gradually leak away.

More In 1911, Victor Hess, a physicist from Austria, began a series of Daring balloon flights that would eventually take him and his instruments to At an altitude of more than three miles, about half the cruising altitude of a commercial airliner, as he ascended, Hess measured the presence of particle radiation charged as that produced by radioactive materials. At first, the radiation decreased with height exactly as expected, but then there was a surprise. From about 1500 meters, the situation was reversed. Hess discovered that there was more radiation than at sea level and that it was increasing with altitude. By the time Hess landed, there was no longer any doubt that the Earth was bathed in radiation from above, and a new field of science was born.

Scientists finally began to call the mysterious space radiation, cosmic rays, a laugh. By the 1930s, the invention of the Geiger counter had made it clear that cosmic rays were hitting the Earth at an astonishing rate amounting to tens of thousands of particles. incomings per square meter every second, most of the time. The particles had relatively little energy, but some had enough energy to pass through rock or even up to a meter of lead. Then in 1938, French physicist Pierre OGE took some Geiger counters high in the Alps to measure cosmic rays and discovered that when two Geiger counters were placed far apart they sometimes recorded cosmic rays arriving at exactly the same time as OJ had discovered cosmic ray showers, bursts of particles that fell in larger and larger showers following the destruction of a single, much more energetic particle high in the atmosphere, based on Due to the size of these showers, some of the rays Cosmic particles from deep space were clearly more energetic than any particles produced on Earth.

Now scientists found themselves embarking on a new quest to understand where in the universe those energetic particles came from, thousands of light years away. from Earth a massive star ends its life in a bright foreign explosion this is a supernova a stellar cataclysm that is one of the most energetic phenomena in nature as the powerful shock wave expands creates a corona of bright gas like this called Cassiopeia here revealed in surprising detail by the Hubble Space Telescope, but could such an event also give rise to cosmic rays? The enigma of cosmic rays is being solved in stages.

The ultimate goal remains to understand how these high-energy particles from beyond our solar system are created. But to get there, scientists first had to figure out what kind of particles they were together. Most of those particles never reach us here on Earth, but instead hit the atmosphere and unleash a torrent of secondary particles that fall like subatomic shrapnel. By studying these secondary particles in the 1930s and 1940s, scientists gradually got closer to the true nature of cosmic rays. What they discovered is that most cosmic rays, about 90 percent of them, must be single protons. Protons are positively charged particles that are part of every atom in the universe, but most of them come in the form of hydrogen atoms, atoms that are made up of a single proton orbited by a single electron, hydrogen is the most Abundant in nature, stars are composed primarily of hydrogen, as are the vast clouds of gas streaming out of the universe. what new stars form, so whatever it is that produces cosmic rays and sends them our way has a lot of raw material to work with.

In 1947, a high-altitude balloon experiment revealed that most of the remaining 10 percent of cosmic rays are made up of the nuclei of heavy atoms. Like iron, like protons, these atomic nuclei are stripped of their electrons and sent through space by a powerful force, but even solar flares, the giant explosions that erupt from the surface of the Sun, cannot explain the energies behind these heavier cosmics. solar rays, but solar flares offer us a clue about how cosmic rays are created because solar flares are caused by the release of magnetic energy. Under the right circumstances, a magnetic field can be used to accelerate an electrically charged particle, such as a proton, to enormous speeds.

This principle is at work at the Large Hadron Collider, the world's largest particle accelerator, where huge superconducting magnets are used to send protons around a giant ring 27 kilometers in circumference. When protons collide, the release of energy is enormous, generating new particles that allow scientists to explore the fundamental properties of matter. Surprisingly, some of the highest energy cosmic rays are millions of times more energetic than the protons at the Large Collider. Hadrons, meaning that somewhere in space nature has created its own particle accelerators that would dwarf anything humans have built on Earth. But identifying them has proven to be a major challenge.

Starting in the 1980s, an experiment called fly-eye in the remote Utah desert used sensitive detectors to detect theFaint ultraviolet glow from cosmic ray air showers high in the atmosphere, allowing researchers to see which direction any particular was facing. Cosmic rays came from the sky, but this did not help scientists figure out where cosmic rays ultimately came from. The reason is that the space between stars is a complex network of magnetic fields that make their way around our galaxy and these fields have been bent and twisted by the turbulent motions of ionized interstellar gas, the magnetic fields completely altering the directions of cosmic rays moving through the galaxy, so that from Earth's point of view they appear to come from all over the sky, leaving no clue as to where they originally came.

In their efforts to explain cosmic rays, scientists had run into a major obstacle that would force them to search the heavens in a new and different way. This is our galaxy, the Milky Way, home to hundreds of billions of stars and vast clouds of dust and gas. that extend over thousands of light years is a huge and complex system, somewhere hidden in its depths are the sources of high energy particles that we call cosmic rays already in 1949 the nuclear physicist Enrico Fermi proposed the idea of that cosmic rays are produced when protons and other charged particles are accelerated to high speeds by bouncing within a changing magnetic field, but where in the Galaxy might conditions make such bouncing possible because cosmic ray particles are intensely energetic , the sources that create them must somehow be able to provide that energy, and those sources can also reveal themselves by emitting a high-energy form of light called X-rays.

Here on Earth, X-rays from space are absorbed by our atmosphere, so what X-ray telescopes must do their job orbiting high above the Earth's surface today, the Chandra. The X-ray Observatory is our most demanding X-ray eye in the sky. Chandra has been used to observe some of the hottest and most energetic regions of the Galaxy, revealing views like this one of the Karina Nebula, where interstellar gas cooks at millions of degrees. for newborn giant stars, this is a high-energy environment, but not one that has the kind of magnetic fields needed to accelerate cosmic ray particles, so instead of looking at the places where stars are born, star hunters Cosmic rays have been focused on those places where giant stars have died.

This spectacular ring is the remnant of a supernova, a vast stellar explosion that sprays matter in all directions creating a rapidly expanding shock wave. The leading edge of this abyss can move at tens of thousands of kilometers per second, but it is still nowhere near the speed. of a cosmic ray particle, however, scientists after Fermi realized that supernova shock waves can compress and strengthen the magnetic fields in the surrounding gas, then the charged particles moving back and forth Through the shock wave they can capture more and more energy through a process called Fermi acceleration, eventually the particles would move fast enough to separate from the shock wave and fly towards the galaxy.

There was finally a theory that could explain cosmic rays, but proving it would require another type of space observatory. That Observatory is NASA's Fermi Space Telescope, named after Enrico Fermi, which has special detectors that can capture gamma rays, a form of light even more energetic than X-rays. The Fermi telescope has been used to study the most extreme phenomena of the universe, such as the supers found in the centers of distant galaxies. or mysterious explosions known as gamma ray bursts and Fermi has also focused its attention on two of the most interesting supernova remnants in the Milky Way: one is w44, a spectacular layer of expanding gas located 10,000 light years away, in The constellation of Aquila, the Eagle, the other is ic-443, nicknamed the Jellyfish Nebula, is located about 5,000 light years away, in the constellation of Gemini.

What these two colorful bubbles have in common is that they are both the result of supernova explosions that expand forming dense clouds of interstellar gas, in theory this should be the perfect situation to generate cosmic rays by the Fermi acceleration of the Fermi spacecraft. It is the perfect tool to test this idea. Its sensitive detectors can distinguish between gamma rays that are produced by different types of strange physical processes, but it would take more than four years of collecting data with Fermi for scientists to be sure. Finally, in February 2013, they were ready. To reveal their results what they had found was a clear signal the first time ever seen of protons at high energies occasionally colliding to produce gamma rays.

The type of signal matched exactly what would be expected if the protons were being accelerated on their way. to become cosmic rays 100 years after cosmic rays were first discovered, the Fermi telescope had finally caught a glimpse of the creation of cosmic rays. Scientists now know more than ever about cosmic rays, but the search does not. end up here, although they are rare, the highest energy cosmic rays are so powerful that not even a supernova shock wave is enough to propel them, so now the search for new sources of cosmic rays is reaching beyond the limits of the Milky Way, outside a giant galaxy. 60 million light years away from us, deep in its core lies a black hole so enormous that its mass is equivalent to more than 6 billion suns as it devours gas from the surrounding environment.

The rapid spin of the black hole causes some of the gas to escape and form. a jet that extends hundreds of thousands of light years into intergalactic space. The jet is enveloped in magnetic fields that may be strong enough to create what are known as ultra-high-energy cosmic rays because they are so rare that experiments that They are looking for these huge particles covering thousands of square miles in an effort to capture just a handful of nature's most energetic particles, but if the theory proves correct for the first time, these experiments could show that we are being hit by matter from another galaxy thanks to After the discovery of cosmic rays, we know that we have a direct connection with some of the most powerful phenomena in the universe.

Now, as a new chapter of exploration opens before us, we are learning how surprising and strange that link with the cosmos can be. summer of 1950 and at the US government laboratory in Los Alamos, New Mexico scientists break for lunch abroad years before, this was the home of the Manhattan Project, the top secret effort to build the first bomb atomic, but now, in a lighter moment, the discussion at one table has become flying saucers. Gins with a humorous story involving aliens, but soon scientists are debating when it would be possible to travel to the stars. Among those present is Enrico Fermi, a Nobel Prize-winning physicist whose many contributions included the development of the world's first functional device.

After a while, the conversation turns to more earthly topics, and Fermi suddenly blurts out a question: where is everyone? Fermi was still thinking about aliens and had just realized something wasn't right. Fermi then did some quick calculations about the location that confirmed his suspicions that if there were advanced extraterrestrial civilizations elsewhere in the galaxy, it is likely that we would have already detected some signal from them, perhaps signals from various civilizations. The fact that it hasn't happened now is called the Fermi paradox after the man who posed the question. Fermi was not the first person to wonder why we have not yet seen signs of extraterrestrial life in the universe, but as a talented scientist he raised the problem of In a way that will resonate far beyond that lunchtime conversation, more than six decades later, the Fermi paradox remains unsolved even as evidence has accumulated that the basic ingredients for life, including carbon, Oxygen and nitrogen are among the most common elements in the galaxy.

Astronomers have also discovered hundreds of planets beyond our solar system and directly observed the rotating disks around young stars. where new planets are forming right now All this new data continues to suggest that if life happened once right here, it must have happened many times, increasing our chances of contacting an advanced civilization. This optimistic reasoning is further reinforced by the fact that life on Earth has a long history, thank you, we know from fossils that over the eons many different types of creatures have called this world home and that Evolution has been very effective in ensuring that life continues to adapt and flourish with changing conditions.

The first traces of life do not come from fossils, but microscopic patterns and chemical traces in ancient rocks show that bacteria were already living on our planet at least 3.5 billion years ago, meaning that the first cells and the first DNA They must go back even earlier, no more than 4.6 billion. years, that's how long it formed along with the other planets from the debris surrounding an infant Sun after allowing a few hundred million years for Earth's surface to cool and its atmosphere to stabilize, it seems. that life must have appeared here almost as soon as it was possible to do so, the key ingredient was water in liquid form.

Water is an ideal solvent where molecules that are important to biology can interact and react due to the early and sustained presence of liquid water. Life was able to take hold. Earth and Earth may not have been alone in August 2012. NASA's Curiosity rover landed in Gale Crater on Mars for the next few months as it meandered across the crater's dusty floor. Curiosity found compelling evidence that the rock beneath its wheels had formed in standing water. The presence of clay minerals in the Rock suggests that the water was similar to fresh water on Earth and was hospitable to life.

This is a far cry from proving that there was ever life on Mars, but it does mean that for some period of time in the distant past. Mars was a habitable planet, at least habitable for microorganisms; Some suspect that there could still be Martian life today, barely existing deep underground, so in our own solar system it appears that life arose in one or possibly both places where there was an environment that could support it even. If Mars is a dead world that has a score of 50 and in a galaxy full of billions of planets it is difficult to imagine that life has not been equally successful among the stars, but as Fermi realized, there must be a problem , maybe It was just a matter of looking for E.T the right way, looking deep into the universe, astronomers have come face to face with the immensity of time, observations of distant galaxies reveal that we live in an expanding universe, measuring the pace of expansion that cosmologists now reveal.

We estimate that our universe began with an event called the Big Bang that took place about 13.8 billion years ago. Our deeper views of the cosmos also reveal that 500 million years after the Big Bang star and galaxy formation was already underway, if that is so. The galaxy probably began to form around that time. Strange contrast. Our solar system is less than 5 billion years old. It has existed for less than half the age of the Milky Way. This would seem to suggest that there has been plenty of time for other civilizations to emerge. inside the Milky Way galaxy long before ours, so when it comes to finding someone else we can talk to, time should be on our side, we have the Fermi Paradox, the surprising riddle that asks if life is so abundant on Earth and if the galaxy has been around for so long, why have we still not seen any signs that there was anyone out there in 1950?

Fermi's question was originally

spark

ed by a conversation among physicists about traveling to the stars, but even if interstellar travel is impossible or impractical due to the great distances involved, the Fermi paradox still holds because the technology already exists to probe the galaxy in search of radio signals from extraterrestrials. Around the time Fermi asked his famous question, astronomers were already planning to build giant radio antennas to probe the heavens for the first time. in history Humanity had an ear to the cosmos in 1960 TheAmerican astronomer Frank Drake was using a 26-meter dish in Greenbank, West Virginia, to listen for any radio emissions that might come from alien civilizations.

It was the beginning of the search for extraterrestrial intelligence. Drake He didn't expect to hear a message specifically intended for us, but he knew that Earth was sending many signals in the form of commercial transmissions and military radars. A civilization even slightly more advanced than ours could be emitting much more from the start. presented a huge needle in the haystack problem, it was one thing to have the right type of antenna to listen to E.T, but quite another to know where to point it and which of the billions of possible frequencies to listen to Drake's approach should be aimed to a couple of the closest stars that seemed similar to our sun and to choose frequencies close to 1420 megahertz the frequency of radio waves emitted by hydrogen the most common atom in the universe when Frank Drake began his search the enthusiasm for configuration was growing as no one had looked.

Before it was possible for the skies to be flooded with signals from well-established civilizations, all talking to each other in a galactic social network, perhaps the answer to the Fermi paradox was simply a matter of turning on a radio receiver, but that is not so. What happened? Drake's initial search came up empty, as did all subsequent efforts to pick up extraterrestrial radio signals, at least so far. One of the most extensive was Project Phoenix, which used satellite dishes in Australia and the United States to probe some 800 carefully selected star systems. The project completed in 2004, scientists concluded that if an advanced civilization was using radio transmission to announce its presence anywhere within 200 light years of Earth, we would have discovered it by now;

By comparison, the Milky Way is more than 100,000 light-years across, so there are still plenty of galaxies to look for, but our ability to collect and filter radio signals from space is becoming increasingly efficient, driven primarily by by Moore's Law, which projects a doubling of computer processing speed approximately every 18 months in California. Scientists at the Seti Institute are developing The Allen Telescope Array will greatly improve the speed and volume of radio-based searches. If technology continues to improve at the current rate, by the middle of this century humans will have heard more than a million star systems if no extraterrestrial civilization appears.

By then, the Fermi paradox will be a more pressing problem than ever and we will have to consider why the chemical and biological processes that led to our emergence have not been repeated elsewhere or at least not frequently enough for us to find someone to talk to. Our existence on Earth demonstrates that life is possible in the universe, what it does not tell us is how likely life is. 2009 NASA's Kepler spacecraft found evidence of thousands of planets in the small section of sky where it turned its gaze, although many of its findings still need to be confirmed with follow-up observations.

Figures suggest that throughout the Milky Way there are tens of billions of foreign planets similar in size to Earth, but we also know that there cannot be billions of civilizations trying to make contact with us. or we would have already heard from some of them where they are is the way Enrico Fermi once asked the question the potential for so many civilizations in our galaxy is it really plausible that we could be alone for decades since Fermi posed there the famous paradox of him ? There have been many attempts to solve it. One set of explanations explores the possibility that extraterrestrials exist but are unable or unwilling to communicate with us, for example, there may be intelligent life on other planets without advanced technology or in a perhaps underwater environment.

When radio communication is not practical, we may also be overestimating the interest that extraterrestrial civilizations may have in contacting us as societies become more advanced, perhaps also becoming more introspective. I have suggested that the aliens are very aware of us, but are silently monitoring us. Like scientists studying another species in its natural environment, the problem with all this speculation is that for every society we can imagine that doesn't want to say hello for some reason, we can also imagine others that do it for us, curiosity and communication have had enormous consequences. Survival benefits The more information we can gather about our environment, the better we can prepare for unknown threats or take advantage of the resources presented to us.

It stands to reason that at least some extraterrestrial civilizations must be curious and interested in communicating. We can even imagine that such a civilization would send probes to the stars in 2013. Voyager 1 became the first human-built probe to reach the edge of the solar system and cross into interstellar space. With a few centuries of improvements in our technology, we could ship them much faster. and more sophisticated probes to the stars these probes could be equipped with instructions on how to find a moon or an asteroid with suitable resources for the probes to make copies of themselves that would be sent to further explore the idea of ​​a self-replicating machine was the first suggested by mathematician and computer science pioneer John Von Neumann, if such machines could be built to travel through space at 140 times the speed of light, about 400 times faster than Voyager 1, after a few million of years they would have visited all the star systems of the Milky Way.

Wow, but that's just a blink of an eye in the life of our planet. The fact that we have found no evidence of Von Neumann machines in our solar system suggests that no one has built them, which in turn means there can't be many. Advanced civilizations that exist or someone would have done so already, this type of reasoning has focused attention on the history of life on our world and the remarkable chain of coincidences that has given our species virtual dominance over our entire planet, such perhaps we are more special than We believe that some have noted that although life emerged quickly on Earth, complex multicellular life took billions of years to appear, if a planet cannot maintain a stable environment for that long, then perhaps the best it can achieve is to host a world. of bacteria in 2000, astronomer Don Brownlee and paleontologist Peter Ward observed how many things have to go right to have a planet like Earth.

They concluded that while simple life may be very common throughout the Universe, complex life is an exception, they called their idea the rare one. Earth hypothesis and in the next decade we may have a clue as to whether they are right after the Kepler mission. Scientists at the Massachusetts Institute of Technology are developing the Transiting Exoplanet Survey Satellite, or Tess for short, which will aim to detect Earth-like planets crossing in front of nearby stars if there is life on those planets, including follow-up observations of microbial life. She can detect traces of it simply by analyzing starlight passing through the planet's atmosphere if Tess finds planets that might be hospitable. bacteria but nothing else then it is possible that we are living in a rare earth universe, of course, there is one more way to solve the Fermi paradox and it is to consider that the technology necessary to make contact with another civilization can go hand in hand with the Technology that would allow a civilization to self-destruct We have so far managed to avoid blowing ourselves up, but given the increasing pressure we are putting on our planet, it is fair to say that our survival is far from guaranteed.

Foreigners' explanation of the Fermi Paradox is that it arose in a conversation between brilliant scientists working in a military laboratory at the height of the Cold War, which should remind us that the Paradox is not just a curious quirk of the cosmos but an important warning to all. our civilization at least. The Fermi Paradox tells us that long-lasting civilizations can be exceptionally rare and that it will take great perseverance on our part to become one, if we are successful and one day pick up a message from another intelligent species. If we have double reason to celebrate, it will mean that we are not alone and that thanks to our careful self-preservation they are not alone either.

It's February 2013 and alone at Vandenberg Air Force Base in California, a rocket rises under a clear sky as the countdown begins. tension in the air It's a perfect day to go to space, but with so much riding on this launch there's good reason for mission controllers to be nervous: The Atlas V rocket carries an advanced space explorer with cameras that can look in multiple wavelengths and reveal hidden details that the human eye cannot see If this mission fails Decades of innovative science will be at risk, but if successful it will greatly strengthen our understanding of the most interesting planet in the solar system, the planet is Earth, only the latest in a long line of spacecraft that have transformed the way we see our home world and that is precisely why there is so much at stake now that this Landsat 8 Mission is not just about launching another satellite, but about preserving a dynasty of data that the Landsat program has already been running. for more than 40 years providing an uninterrupted record of our planet during a period of astonishing change now with Landsat 8.

Researchers hope to extend that record for many years into the future. In the process, they may witness a transformation more profound than anything they imagined when the Landsat program began abroad. It was a beginning inspired by a very different goal. In the early 1960s, the Soviet Union was leading the space race and the United States was sparing no expense to surpass its rival superpower. The goal was to be the first to land a manned spacecraft on the moon. But along the way, the United States first had to master the basics of launching its astronauts into orbit.

The first flights were solo and the astronauts briefly had relatively little time to absorb the incredible views they were getting while looking down at Earth, but that began to change in 1962 at the end of the Mercury program, by which time American astronauts were equipped with cameras. high-quality laptops and had time to use them. The final Mercury mission lasted more than 34 hours. The resulting photographs were stunning, especially in an era when scientists still used black-and-white aerial photographs to study Earth's terrain when the Mercury program transitioned to the Gemini program. Orbital flights became longer, sometimes lasting several days, and photography improved further in 1966.

The Gemini astronauts had taken about 1,100 images by pointing their cameras at the mountains. lakes, deserts and coastlines their images often showed remote regions of the Earth in focus and sharpness that were difficult to access and little studied these images were not only impressive, but were clearly useful to scientists before images taken from orbit they would have been used primarily to observe weather patterns. Now researchers were beginning to understand the benefits that could come from having a satellite dedicated to exploring the Earth's surface from space. One of the main proponents of the idea was William Pecora, director of the United States Geological Survey.

Mura could see that the Space Program had the potential to greatly improve our knowledge of the Earth's natural and agricultural resources and this was just as population growth and industrialization around the world were making such information vital. importance, so in September 1966 Pakora pressured the US Department of the Interior to reveal a new space observation program. The centerpiece was called the Earth Resources technology satellite, but not everyone was excited about the idea, as NASA had already invested deeply in a manned mission to the Moon. Government administrators were reluctant to spend even more money on another completely different space project.

Others were concerned about the legal and political consequences. implications of launching a satellite that could view other nations' territories up close from orbit and then there was the US military which had already been operating its own series of spy satellites since 1959. Defense officials were not in absolutely eager for the public to understand the remarkable power of surveillance from space despite theseObstacles The idea of ​​an Earth observation satellite for civilian use gradually gained support. In 1970, NASA got the green light to build such a spacecraft. Its design was a modified version of the weather satellites that had already been flying since 1964. , but this spacecraft was equipped with cameras capable of imaging features on the Earth's surface up to 80 meters in size, in both visible light and near-infrared, and included a recorder to play back data collected from virtually any point on the planet. balloon. quickly and on July 23, 1972 the Earth Resources technological satellite erts-1 was successfully launched into orbit.

Sadly, William Pakora, the geologist and federal administrator who had pushed so hard for the mission, had died in the hospital just days earlier when he was 59 years old. I had the opportunity to witness the scientific results of the satellite that was later renamed Landsat 1, but the results were impressive and for the next five and a half years, Landsat 1 would provide a treasure trove of data about our planet and it was not alone in 1975. It was launched Landsat 2, increasing the program's reach and extending its lifespan by another five years into the future. That pattern would continue with a series of overlapping missions into the 1980s and beyond, and at some point not too soon, Landsat may have been born outside of space.

Race, but he would come of age just as scientists were racing to understand the profound environmental changes taking place on Earth thanks to Landsat. They would have a front-row seat off the coast of Labrador. A small speck of land less than 50 meters wide looms above the frigid waters unexplored after centuries of maritime exploration, it was finally detected by Landsat 1 in 1976. To this day it is called Landsat Island since it began in 1972, The Landsat program has added countless details like this to our map of the world, but the real value of the Landsat program comes not from putting new places on the map but from seeing what's on the map in a completely new way.

Each Landsat spacecraft is equipped to view the Earth's surface in multiple wavelengths of light, including some that are beyond the range of normal human vision. By assigning different contrasting colors to these wavelengths, researchers may be able to highlight details that would be too subtle to detect in a normal color photograph. Here, for example, a small but lush corner of Oman stands in stark contrast to the arid desert that surrounds it. The region is different from the rest of the Arabian Peninsula because the mountains here capture the monsoon rains during the summer and supply water to a rich, fertile strip of coastal lowlands.

Elsewhere, this brightly colored section of Axel Hyberg Island and Canada's High Arctic shows the extent of frozen glaciers. Here, seen in blue among the island's rugged mountains, which appear in yellow, the satellite can also reveal other more ephemeral features, here freshly transported river sediments form ghostly ribbons in the Mississippi delta, while here in the Ocean Pacific, about 600 kilometers west of Chile, the wind blows over a remote place. The island forms a repeating pattern of swirls in the clouds. There's no doubt that Landsat has given us a dramatically different perspective on Earth's natural geographic diversity, but even more telling is the way the program has documented humanity's growing impact on the planet. scale that we can only capture its true impact by observing it from space.

Nowhere is this more true than the RLC, once the fourth largest lake in the world. A vast Inland Sea that was the size of Ireland, although it has existed for thousands of years. has virtually disappeared in just a few decades because the rivers that feed the RLC have been largely diverted for irrigation. This succession of Landsat images captures the RLC's disappearing act as the waters shrink into oblivion, taking away a once-thriving fishery and leaving behind an arid zone. The salt desert lens has also proven crucial in documenting a very different type of loss in the Amazon Basin: the clearing of vast tracts of rainforest for logging and agriculture.

This sequence shows how that process has played out in Rondonium, a state in northwestern Brazil where the rainforest is first divided in a herringbone pattern as logging roads extend into undisturbed territory, then parceled sections of forest are systematically removed outside. About 16 percent of the Amazon rainforest has disappeared since Landsat began. Images of the region elsewhere Landsat images have witnessed the increasing scale of development around the planet, for example the city of Las Vegas can be seen spreading rapidly across the Nevada desert, exerting great pressure on the water supply in one of the driest regions of the United States, meanwhile, halfway around the world, a new lake is forming behind China's three huge ones. magnificent dam completed in 2012 this huge hydroelectric project displaced more than 1 million people around the world searching for energy and its consequences are a recurring theme that produces some of the most impressive landsat images in the wilderness of northern Alberta the landsat notes vast swaths of land along the Athabasca River are open to oil drilling and, along the Persian Gulf, the wealthy Emirate of Dubai, a product of the Middle East oil boom, is showing some Geographic Art by creating islands artificial palm trees and a clear world map.

On the real world map, the continued use of oil and other fossil fuels is having a profound effect on the planet. Here Landsat documents the surprising retreat of the Columbia Glacier in Alaska as global warming intensifies with rapid melting of ice and rising sea levels appears to be the cause. Inevitable outcome, but just as our awareness was growing about the magnitude of this change, Landsat's invaluable perspective on our planet was at risk of disappearing forever as humanity faces global warming, the ability to continuously monitor the surface of the Earth from space has become an essential element. starting point for any future efforts to manage the planet's resources and preserve its invaluable biodiversity.

The Landsat program is tailor-made for this purpose because Landsat images are relatively wide-angle and do not show details as fine as individual trees or buildings, Instead, Landsat offers a Panoramic View that aims to capture changes at a regional scale. Each satellite in the series was designed to circle the Earth in a polar orbit, allowing it to image the world in a series of north-south swaths starting with Landsat 3. Each satellite was placed. In an orbit that is just over 700 kilometers above the Earth's surface, the orbit is also synchronized with the Sun, so that whenever the satellite passes overhead during the day, the local time below is around 10am.

The orbit means that a satellite can obtain images of any particular location on the planet every 16 days and always at the same time of day. This is especially useful for tracking long-term trends because each time an image of a particular location is captured, the illumination angle is approximately As before, because of this visual continuity, the Landsat database becomes more valuable. the longer it builds up, which is why researchers were especially concerned when Landsat 6 failed during its launch in October 1993. The Landsat program had already narrowly escaped being shut down for budgetary reasons, and although Landsat 5 still works well, it had already been in space for nine years, it would have to last six more years before the United States was ready to finance the construction and launch of Landsat 7 in 1999.

That launch was a success, but a few years ago. Later, the failure of a crucial piece of hardware meant the spacecraft was left partially blinded and its images incomplete. It would be a long, hard battle to get the next Landsat approved when it was ready to fly in 2013. Landsat 8 was not only the most sophisticated. satellite of the series and was also a rescue mission for the entire program; Then, just six weeks before the big launch, Landsat 5 finally shut down after a record 28 years of observing, stopping communicating with mission controllers in January 2013. That meant only Landsat 7 was abandoned and already was not operating at full capacity, so in February, with Landsat 8 on the launch pad, the fate of the entire program hung in the balance, charging skyward on a plume of white smoke, the rocket carried its Precious Charge to orbit.

Shortly after, the good news was confirmed. Landsat 8 was successfully launched and its systems were operating normally. The scientists were elated and relieved. Over the next few weeks, the new Mission would show its prowess by sending back even more spectacular images than its predecessors in May 2018. The satellite was fully operational, returning more than 400 images per day. These first images from Landsat 8 make it clear that the entire program has begun a new chapter and that Landsat's continued coverage will likely prove invaluable as we move into a period of unprecedented global change. For now, Landsat is not the only Eye in the Sky monitoring our planet every minute we are surrounded by a series of Earth observation satellites like Terra, a multinational spacecraft operated by NASA that has specialized sensors to monitor the change. environmental or, like Canada's radar satellite program, a series. of satellites that can see the Earth both day and night, its Vision radar penetrates clouds and fog to create spectacular high-resolution images of the surface and sees how things have evolved since the earliest days of Earth.

It is clear that we are now in a period of specialized planetary monitoring, one that no satellite could handle alone, but Landsat with its ever-expanding record of our world still provides an underlying basis for an entire Earth observation system, Ultimately, that's where Landsat's biggest impact lies. Starting the program decades ago, researchers were not only creating a camera to photograph the Earth from space, they were actually creating a new field of science: the science of remote sensing and, as the pace of environmental change accelerates around the world, it is increasingly clear that this is a science we cannot do without.

Thank you.