Astronomy and Stars
Discussions about astronomy and stars. As we look further out what can we find in the universe beyond Earth's atmosphere?
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Sometime during the third century, a brilliant burst of light from the explosion of a massive star was visible from Earth. If the supernova blast had flashed over the northern hemisphere, it might have been considered an evil omen. At that time, Western Civilization was in upheaval. The Roman Empire was beginning to crumble. An emperor was assassinated, followed by political upheavals, civil wars, and barbarian attacks. But the violent supernova death could only be seen in the southern skies. The blast occurred in the nearby satellite galaxy, the Small Magellanic Cloud. No record exists of the titanic event. However, like the smoke and ash drifting across the sky afte…
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How dark is the sky, and what does that tell us about the number of galaxies in the visible universe? Astronomers can estimate the total number of galaxies by counting everything visible in a Hubble deep field and then multiplying them by the total area of the sky. But other galaxies are too faint and distant to directly detect. Yet while we can’t count them, their light suffuses space with a feeble glow. To measure that glow, astronomers have to escape the inner solar system and its light pollution, caused by sunlight reflecting off dust. A team of scientists has used observations by NASA’s New Horizons mission to Pluto and the Kuiper Belt to determine the brightness o…
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In 1995, the Hubble Space Telescope stared at a blank patch of the sky for 10 straight days. The resulting Deep Field image captured thousands of previously unseen, distant galaxies. Similar observations have followed since then, including the longest and deepest exposure, the Hubble Ultra Deep Field. Now, astronomers are looking ahead to the future, and the possibilities enabled by NASA’s upcoming Nancy Grace Roman Space Telescope. The Roman Space Telescope will be able to photograph an area of sky 100 times larger than Hubble with the same exquisite sharpness. As a result, a Roman Ultra Deep Field would collect millions of galaxies, including hundreds that date back t…
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When NASA's Voyager 2 spacecraft flew by Neptune in 1989 after a nearly 3-billion-mile odyssey, astronomers expected to get a close-up look at a blue-green planet that seemed as featureless as a marble. Instead, they were shocked and intrigued to see a dynamic and turbulent world of whirling storms, including a giant feature dubbed the Great Dark Spot, looming in Neptune's far southern hemisphere. The vortex was reminiscent of Jupiter's legendary Great Red Spot, a monstrous storm that has been raging for hundreds of years. Had this Great Dark Spot been brewing for the same amount of time? Or, was it a more ephemeral tempest? Scientists had to wait until 1994, when the…
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Though every planet in our solar system has been visited by spacecraft over nearly the past 60 years, the outer frontier of the solar system, beyond Neptune, has been barely explored. There is circumstantial evidence that a planet five times Earth's mass – dubbed Planet Nine – may be lurking out there in the abyss. If real, it is creeping along a very wide orbit taking it 800 times farther from the Sun than Earth is. Though astronomers have yet to find this legendary world – if it exists at all – they have found another clue 336 light-years away. Astronomers analyzing Hubble images of the double star, HD 106906, have discovered a planet in a huge 15,000-year-long orbit …
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Great things take time. This is true when it comes to many processes in the universe. For example, it takes millions of years for stars—the building blocks of the universe—to form. Then, many stars last for billions of years before they die and begin to eject shells of gas that glow against the vastness of space—what we call nebulas. It can be exceedingly rare to capture some of these processes in real time. Lucky for us, it seems as if the Stingray nebula, Hen 3-1357, was destined to stand out from the crowd since its beginnings. It was dubbed the youngest known planetary nebula in 1998 after Hubble caught a rare peek at the central star’s final stages of life. Now, tw…
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Black holes are the universe's monsters: voracious eating machines that swallow anything that ventures near them. These compact behemoths pull stars and gas into a disk that swirls around them. The feeding generates a prodigious amount of energy, producing a powerful gusher of light from superheated infalling gas. These disks are so far away that it's nearly impossible to discern any detail about them. But by a quirk of alignment, astronomers may be getting a glimpse of the structure of the disk around the black hole in nearby galaxy IC 5063. The Hubble Space Telescope has observed a collection of narrow bright rays and dark shadows beaming out of the blazingly bright…
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In our infinite universe, stars can go bump in the night. When this happens between a pair of burned-out, crushed stars called neutron stars, the resulting fireworks show, called a kilonova, is beyond comprehension. The energy unleashed by the collision briefly glows 100 million times brighter than our Sun. What's left from the smashup? Typically an even more crushed object called a black hole. But in this case Hubble found forensic clues to something even stranger happening after the head-on collision. The intense flood of gamma-rays signaling astronomers to this event has been seen before in other stellar smashups. But something unexpected popped up in Hubble's near…
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Stars are not created equal. They span a broad range of sizes, ages, and temperatures from diminutive red, cool, low-mass stars to opulent blue, hot, massive stars. Our Sun is roughly midway between these populations. Because stars are the universe's LEGO blocks for building immense galaxies, astronomers are always seeking a much better understanding of their birth and death. Stars' behavior over their lifespan relates to everything from planets to the formation and evolution of galaxies. To better understand stars and their evolution, the Space Telescope Science Institute has launched an ambitious new initiative with the Hubble Space Telescope called ULLYSES (UV Legac…
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In our infinite universe, if you can imagine something, you may eventually find it out there. And, that even goes for celestial objects that look like some creepy incarnation straight out of a Halloween tale. Hubble's holiday offering is a pair of colliding galaxies that resemble the cartoon Peanuts character Linus's imagining of the elusive Great Pumpkin. "Great" is an understatement in this case because the galaxy pair spans 100,000 light-years. The "pumpkin’s" glowing "eyes" are the bright, star-filled cores of each galaxy that contain supermassive black holes. An arm of newly forming stars embracing the pair gives the imaginary pumpkin a wry smirk. In about 6 billion …
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New Survey Finds that Single Burst of Star Formation Created Milky Way’s Central Bulge
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Like most spiral galaxies, the Milky Way has a roughly spherical collection of stars at its center called the bulge. How the bulge formed has been a long-standing mystery, with many studies suggesting that it built up over time through multiple bursts of star formation. New research finds that the majority of stars in our galaxy’s central bulge formed in a single burst of star formation more than 10 billion years ago. To reach this conclusion, astronomers surveyed millions of stars across 200 square degrees of sky—an area equivalent to 1,000 full Moons. The resulting wealth of data is expected to fuel many more scientific inquiries. View the full article
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Now you see it, now you don't. Though stars explode at the rate of one per second in the vast universe, it's rare to get a time-lapse movie of one fading into obscurity. This disappearing act, in a galaxy 70 million light-years away, was captured by the Hubble Space Telescope as part of a program to measure the universe's expansion rate. More than just providing celestial fireworks, supernovae can be used as milepost markers to measure distances to galaxies. This yardstick is needed to calculate how quickly galaxies appear to be flying apart from one another, which in turn provides an age estimate for the universe. The titanic explosion, which briefly outshined the entire…
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More massive than all the other planets combined, Jupiter truly is the king of our solar system. The swirling clouds, arranged in colorful, banded structures, change from year to year. The rich colors are produced by trace compounds in Jupiter’s predominantly hydrogen/helium atmosphere. Hurricane-force winds propel these clouds, and upwelling currents are ablaze with lightning bolts far more powerful than those seen on Earth. The Hubble Space Telescope serves as a “weather satellite” for monitoring Jupiter’s stormy weather. The iconic Great Red Spot, a storm big enough to swallow Earth, shows that it’s shrinking a little in the Hubble images, but it still dominates the …
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While studying the Coma galaxy cluster in 1933, astronomer Fritz Zwicky uncovered a problem. The mass of all the stars in the cluster added up to only a few percent of the heft needed to keep member galaxies from escaping the cluster's gravitational grip. He predicted that the "missing mass," now known as dark matter, was the glue that was holding the cluster together. Dark matter, as its name implies, is matter that cannot be seen. It does not emit, absorb, or reflect light, nor does it interact with any known particles. The presence of these elusive particles is only known through their gravitational pull on visible matter in space. This mysterious substance is the in…
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Looks can be deceiving. The Andromeda spiral, the nearest major galaxy to our Milky Way, can be seen as a small, fuzzy, spindle-shaped object in the autumn skies of the Northern Hemisphere. What can’t be seen because it is too faint is a vast halo of hot, rarified gas that would stretch out from the Andromeda galaxy to the width of three Big Dippers. Now, in the most comprehensive study of the monstrous halo, Hubble astronomers have mapped this tenuous plasma, finding that it has a layered structure, with two distinct, nested shells of gas. They also found that it extends 1.3 million light-years from Andromeda—about halfway to our Milky Way—and as far as 2 million light-y…
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Whether it’s a surprise asteroid, colorful aurora or a heart-stopping eclipse, the landscape of the night sky is constantly changing. When a new visitor appears in view, it’s guaranteed to grab the attention of professional astronomers and casual sky gazers alike. Well, consider the Hubble Space Telescope the paparazzi of the sky, as it’s managed to snap the closest images yet of the sky’s latest visitor to make headlines, comet C/2020 F3 (NEOWISE), after it passed by the Sun. Comet NEOWISE is considered the brightest comet visible from the Northern Hemisphere since 1997’s Hale-Bopp. It’s estimated to be traveling at a whopping 40 miles per second, or 144,000 miles per …
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The aging, bright-red supergiant star Betelgeuse has captivated sky watchers since antiquity. The ancient astronomer Ptolemy was one of the first to note the monster star's red color. It is one of the brightest stars in the night sky and appears even more luminous because it is so close to Earth, only 725 light-years away. But the star also periodically changes in brightness, which was first noted in the 1830s by British astronomer John Herschel. Astronomers now know that the star expands and contracts, brightening and dimming, on a 420-day cycle. However, in October 2019, the star dimmed dramatically and continued to become even fainter. By mid-February 2020, the mon…
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Astronauts who have gazed at Earth from space have been awestruck at our blue marble planet's majesty and diversity. Mike Massimino, who helped service the Hubble Space Telescope in orbit, said, "I think of our planet as a paradise. We are very lucky to be here." What's mind-blowing is that astronomers estimate there could be as many as 1 billion other planets like Earth in our Milky Way galaxy alone. Just imagine, one billion – not million – other "paradise planets." But it's paradise lost if nothing is living there to marvel at sunsets in azure blue skies. And, as 19th century philosopher Thomas Carlyle mused, "…what a waste of space." It is sobering that our home p…
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NASA's Nancy Grace Roman Space Telescope has just successfully completed a preliminary design review of the mission’s ground systems, including the Science Operations Center that will be hosted by the Space Telescope Science Institute (STScI) in Baltimore, Maryland. This means the plan for science operations has met all of the design, schedule, and budget requirements. The mission will now proceed to the next phase: building the newly designed systems that will enable planning and scheduling of Roman observations and managing the resulting data. View the full article
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Watching Saturn and Earth from afar, space alien astronomers would note that Earth whips around the Sun nearly 30 times for every one orbit Saturn completes. That's because Earth is 10 times closer to the Sun than Saturn, and hence caught in the Sun's tighter gravitational grasp. Every time Earth "laps" sluggish Saturn, like two NASCAR racers, astronomers aim Hubble at the glamorous world to get a close-up look. Like Earth, Saturn is tilted on its axis and so goes through seasons. In this snapshot it is summer in the northern hemisphere. Hubble's crisp view shows multiple banded cloud activity warmed increasingly by direct sunlight. The spectacular ring system remains as …
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The "Bat Shadow" is the nickname Hubble astronomers gave to a huge shadow cast by a young star's planet-forming disk in 2018. Resembling a pair of wings, the striking image is actually a shadow on a more distant cloud—like a fly wandering into the beam of a flashlight shining on a wall. Now, the nickname turns out to be even more appropriate, because the team reports that those "wings" are flapping! The phenomenon may be caused by a planet pulling on the disk and warping it. View the full article
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For stars nearing the end of their lives, the forecast is clear: It's time for the fireworks! Planetary nebulas, whose stars shed their layers over thousands of years, can turn into crazy whirligigs while puffing off shells and jets of hot gas. New images from the Hubble Space Telescope have helped researchers identify rapid changes in material blasting off stars at the centers of two nebulas — causing them to reconsider what is happening at their cores. In the case of NGC 6302, dubbed the Butterfly Nebula, two S-shaped streams indicate its most recent ejections and may be the result of two stars interacting at the nebula's core. In NGC 7027, a new cloverleaf pattern …
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In Greek mythology the first deities born from the universe's origin in "the Chaos," created a race of Titans. The powerful Titans were eventually superseded by the gods of Olympus. In modern cosmology, the stellar equivalent of the legendary Titans are so-called Population III stars, that would have been the very first stars born after the big bang. These hypothetical stars are as elusive as the Titans. Unlike the stars of today—like our Sun (that contains heavier elements, such as oxygen, nitrogen, carbon and iron)—the Population III stars would have been solely made out of the few primordial elements first forged in the seething crucible of the big bang. Much more mass…
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About 3.5 million years ago, our distant hominid ancestors might have noticed a mysterious glowing spot along the arc of the star-studded Milky Way. Today we know that this would have been evidence for a tremendous explosion around a black hole that rocked the center of our galaxy. Scientists using Hubble now see the aftermath of that enormous flash of light that beamed out of our galaxy's center way back then. It illuminated a huge, ribbon-like tail of gas orbiting the Milky Way. Called the Magellanic Stream, this long trail lies far outside of our galaxy, at an average distance of 200,000 light-years. Like an aircraft contrail, It extends from neighboring dwarf galaxie…
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One of the top priorities for new home buyers is location. Finding a home in the right neighborhood is a key ingredient for a happy, prosperous family. Like families hunting for a house, fledgling planets also need the proper location to grow and thrive. Astronomers using Hubble to probe the giant, young star cluster Westerlund 2 are finding that stars residing in the system's crowded central city face a rough-and-tumble neighborhood that suppresses planet formation. The Hubble observations show that lower-mass stars near the cluster's core do not have the large, dense clouds of dust that eventually could become planets in just a few million years. But life is a lot e…
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