Jase1        Posted at 2023-03-15 11:38:47(85Wks ago) Report Permalink URL | ||
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| Angular Resolution and What Hubble Can’t See  The crisp, stunning images from the Hubble Space Telescope are a wonder to behold. As one can see in the image comparison below, Hubble’s views are significantly higher resolution than similar images obtained by ground-based observatories.  Ground-based (left) vs space-based (right) images of star-forming regions in the Whirlpool Galaxy. On the left is the view from the WIYN telescope at Kitt Peak in Arizona. On the right is the view from the Hubble Space Telescope. WIYN Image Credit: K. Rhode, M. Young and WIYN/NOAO/AURA/NSF HST Image Credit: NASA, ESA, S. Beckwith (STScI), and The Hubble Heritage Team (STScI/AURA) Terrestrial telescopes must look through Earth’s atmosphere, which blurs the view and limits their resolution. Orbiting above Earth’s atmosphere, Hubble avoids that problem and can get a clearer view of the universe. While Hubble provides the highest resolution of any visible-light telescope, that resolution has a limit. There are many things in the universe that Hubble can’t resolve, and the public is constantly curious about that boundary. One question that we often hear is whether Hubble can see the lunar landers left behind by the Apollo missions (short answer: no). We also get questions asking why Hubble has such poor views of nearby Pluto, when it can get almost 100 million pixels of the much more distant Whirlpool Galaxy. To answer questions like these fully, one must delve into a combination of size and distance called “angular resolution”. Reading the Signs Let’s start with an example from everyday life. When driving along a highway, one can often see signs far in the distance down the road. At first, only the shape and color of the sign are recognizable. Then, one can tell that there is writing on the sign, but it is not possible to make out the words. Eventually, the words become clear enough to read.  The signs on the near bridge are readable, while those on the far bridge are not. The physical sizes of the sign and its lettering do not change. The major change is the distance between the observer and the sign. At a large distance, the sign covers a very small angle in one’s field of view and cannot be read. When close, it covers a large enough angle to be readable. We say that an object “subtends” an angle that depends on its size and distance from the observer. That “angular size” is the important characteristic of the object in this scenario. For the observer, the important characteristic is called “angular resolution”. The angular resolution is a measure of the smallest angle at which the observer can distinguish between two objects (or details within an object). As you probably know, there are 360 degrees of arc in a circle. For measuring small angles, we divide each degree into 60 arcminutes, and each arcminute into 60 arcseconds. The angular resolution of the human eye is about 1 arcminute. The result is that, for the sign along the highway, the words become readable when the letters have an angular size that is several times larger than the angular resolution of the human eye. Hence, the angular size of the letters needs to be several arcminutes. Hubble’s Angle on the Universe These same ideas apply to observations with the Hubble Space Telescope. Hubble has an angular resolution of about 1/20th of an arcsecond. That is a very small angle, but things in the universe can be very, very far away. Objects whose angular size is less than this value are not resolved by Hubble. They are like a cosmic highway sign that is too small and too distant for even Hubble to read.  A comparison of the relative angular size, as seen from Earth, for the Moon, four planets, and two Hubble images. For scale, the Moon is about half a degree in angular size. Let’s address whether Hubble can see the Apollo landers on the Moon. To be seen by Hubble, an object would need to subtend an angle greater than 0.05 arcseconds. The Moon is, on average, about 384,400 km away. At that distance, 0.05 arcseconds is equal to a size of 93 meters (101 yards), or the length of a football field. An object on the Moon must be a few football fields in size, or Hubble cannot resolve it. The Apollo landers are much smaller than a football field, and too small for Hubble to see. Now, what about the images of Pluto and the Whirlpool Galaxy?  Hubble images of Pluto (left) and the Whirlpool Galaxy (right). Note: these images are at wildly different physical and angular scales. At its closest point to the Sun, Pluto is about 30 times farther from the Sun than Earth, which is a distance of about 4.5 billion km. At that distance, an angular resolution of 0.05 arcseconds corresponds to a physical size of just over 1,000 km. Pluto’s diameter is a little less than 2,400 km, making it a little more than 2 pixels in a standard Hubble image. The image above shows about 15 pixels across the diameter of Pluto. One should not be asking why the resolution is so bad, but, instead, why the resolution is so good! The extra resolution in the Pluto image is from the Faint Object Camera (FOC), which was part of Hubble’s instruments from 1990 to 2002 (It was removed during Servicing Mission 3B). Designed to see small, faint objects like Pluto, the FOC instrument had a high-resolution mode that provided 7 times the resolution of the standard Hubble cameras. The limitation of FOC was that it could provide such resolution over a very small field of view, and at shorter wavelengths (green to ultraviolet). As such, FOC was not suited to general purpose imaging, and could not take images like the one of the Whirlpool Galaxy above. The Whirlpool Galaxy is not only much, much bigger than Pluto, but also much, much farther away. Let’s see how the size and distance factors play out in terms of angular resolution. The Whirlpool is about 60,000 light-years across, making it medium-sized compared to the 100,000 light-year diameter of our Milky Way. At that size, the galaxy is around 250 trillion times larger than Pluto. The galaxy’s distance is about 23 million light-years, or about 50 billion times more distant than Pluto. The size difference (250 trillion) is larger than the distance difference (50 billion) by a factor of 5,000. Therefore, Hubble should get around 5,000 x 2 = 10,000 pixels across an image of the Whirlpool. The full resolution of the above image is 11,477 pixels by 7,965 pixels. Hubble’s angular resolution at the distance of the Whirlpool Galaxy corresponds to a large physical distance: over 5 light-years. However, the galaxy is roughly 10,000 times larger than that, and is extremely well-resolved. Size, Distance, and Resolution Physical size of the object is important, but only part of the story. Distance to the object is also a factor, but not enough for the full calculation. The combination of physical size and distance, as expressed by angular size and angular resolution, is the important criterion for determining how well Hubble, other telescopes, or even the human eye will be able to see an object. Using these measures, one can tell that Hubble has no hope of seeing the lunar landers, will just barely discern Pluto, and can view the Whirlpool Galaxy in gorgeous detail. I hope we can now consider these questions resolved. AUTHOR Dr. Frank Summers | |
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| Jase1Posted at 2023-03-16 09:21:38(85Wks ago) Report Permalink URL | ||
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|  “My bet is there was an eruption of a lava lake,” says Robert Herrick, a planetary scientist at the University of Alaska Fairbanks and one of the new study’s two co-authors. As reported today in the in the journal Science, Herrick and a colleague spotted the volcanic maw—on the side of the colossal volcano Maat Mons—in radar images taken by NASA’s Magellan spacecraft in 1991. “This is one of the most convincing pieces of evidence we’ve seen,” says Stephen Kane, a planetary astrophysicist at the University of California, Riverside, who was not involved with the work.  Evidence of ongoing volcanic activity on Venus has existential implications. The planet is much like Earth in size and composition, but its considerable ancient stores of water—possibly in the form of oceans—were vaporized long ago when the planet was scorched during a mysterious cataclysm. Runaway climate change triggered by apocalyptic eruptions remains the prime suspect. By understanding Venus’s present-day volcanism, scientists can learn more about the divergent fates of Earth and its blistering sister world. “If you want to understand the only other Earth-size world we will ever get to, anywhere in the universe, Venus is the only choice you have,” says Paul Byrne, a planetary scientist at Washington University in St. Louis who was not part of the new study. A fleet of Soviet spacecraft revealed Venus to be almost entirely covered in volcanic structures—some Earth-like, others distinctly alien—back in the early 1980s. Hoping to map the planet’s features in unprecedented detail, NASA’s radar-equipped Magellan spacecraft arrived in 1990. By repeatedly orbiting the planet and examining the same places several times, scientists hoped to spot signs of volcanic activity. But there were complications. The low resolution of the radar meant that any physical changes would have needed to be sufficiently big to show up on the images. And early in the mission, Magellan’s orbit began to deteriorate, causing the spacecraft to map less of the surface on each successive trip around the planet. Despite these challenges, 43 percent of the planet was mapped at least twice. But comparing multiple images of the same volcano to look for changes also proved problematic, as the angle of each shot frequently differed between orbits. In the decades following the mission, nobody managed to find a convulsing volcano. “We seem to keep getting teased by these indirect pieces of evidence,” Kane says. But the holy grail—a spewing volcano or a flowing river of molten rock—remained elusive. In 2021 EnVision and VERITAS were selected for launch, thereby becoming the best bet at finding active volcanism on Venus. But Herrick remained impatient. “I had lots of Zoom meetings where I didn’t need to be fully engaged,” he says, referring to the height of the pandemic. “Whenever I had an hour here or there, I just started looking” at the old Magellan data. He manually aligned images of Venus’s volcanoes, searching for anything odd. During one search, Herrick forensically examined Maat Mons. Named after the Egyptian goddess of truth and justice, it is the tallest volcano on the planet—and on one of its flanks, between February and October 1991, something changed. In those eight months, matter appears to have flooded into an open vent, which grew from 0.8 to 1.5 square miles, and a fresh stream of material seemingly oozed downslope. “I think this really is something,” Herrick recalls thinking. He ran it by his co-author, Scott Hensely of NASA’s Jet Propulsion Laboratory, who agreed: something volcanic had stirred. The vent-filling substance could be rocky debris from a landslide. It is also possible that the stream-like feature was already present in the February imagery but could not be seen due to the angle of the images. But the most probable scenario is that in 1991, a huge eruption of lava filled the expanding vent, and some of it poured over the rim or bled through a fissure. “We can definitely say it changed shape,” Herrick says. And when a volcano changes shape that dramatically on Earth, the root cause is always molten rock. “I think what they’ve seen is real,” Washington University’s Byrne says. He suspects that the vent’s alteration could have been due to subterranean movement, such as magma shifting violently below ground, rather than an eruption. Scientists hope to answer a fundamental question: “What is the day-to-day volcanic heartbeat of the planet doing?” Byrne asks. The volcanoes of Earth and Jupiter’s moon Io are always erupting. Mars might erupt once every few million years. Where does Venus fall on that spectrum? The discovery suggests the planet has something closer to a vivacious, Earth-like volcanism. VERITAS and EnVision are set to answer this question, but until then, this study will encourage scientists to peruse Magellan’s records, hoping to find another erupting Venusian volcano. | |
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| BeowulfPosted at 2023-03-16 14:13:51(85Wks ago) Report Permalink URL | ||
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|  A small, dense cloud of gas and dust called CB 130-3 blots out the centre of this image from the NASA/ESA Hubble Space Telescope. CB 130-3 is an object known as a dense core, a compact agglomeration of gas and dust. This particular dense core is in the constellation Serpens, and seems to billow across a field of background stars.  Dense cores like CB 130-3 are the birthplaces of stars, and as such are of particular interest to astronomers. During the collapse of these cores enough mass can accumulate in one place to reach the temperatures and densities required to ignite hydrogen fusion, marking the birth of a new star. While it may not be obvious from this image, a compact object teetering on the brink of becoming a fully fledged star is embedded deep within CB 130-3. Astronomers used Hubble’s Wide Field Camera 3 to better understand the environment surrounding this fledgling star. As this image shows, the density of CB 130-3 isn’t constant; the outer edges of the cloud consist of only tenuous wisps, whereas at its core CB 130-3 blots out background light entirely. The gas and dust making up CB 130-3 affect not only the brightness but also the colour of background stars, with stars towards the centre the cloud appearing redder than their counterparts at the outskirts of this image. Astronomers used Hubble to measure this reddening effect and chart out the density of CB 130-3, providing insights into the inner structure of this stellar nursery. Image description: The image shows an irregularly-shaped bright orange object composed of dense gas and dust, which appears darker and more compact at the centre. This dense cloud, called CB 130-3, is outlined by thinner gas and dust in light shades of blue. The background shows a multitude of bright stars against a black background. Credit: ESA/Hubble, NASA & STScI, C. Britt, T. Huard, A. Pagan & Beowulf  | |
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| Jase1Posted at 2023-03-16 16:41:20(85Wks ago) Report Permalink URL | ||
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| Jase1Posted at 2023-03-16 16:47:19(85Wks ago) Report Permalink URL | ||
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| miokPosted at 2023-03-16 17:08:14(85Wks ago) Report Permalink URL | ||
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| A decade after launch, NASA's Solar Dynamics Observatory delivers a stunning video of the sun.  courtesy of NASA's Goddard Space Flight Center/SDO This weekend, you should probably go stare at the sun. While this would normally be an ill-advised thing to do, thanks to a recently released time-lapse depicting the sun’s solar cycle, you could do this safely while social-distancing from the comfort of your home. In February 2010, NASA launched the Solar Dynamics Observatory (SDO), a first-of-its-kind spacecraft with one job to do: study the sun. Now, using some of the 425 million photos the SDO has collected so far, NASA has created a stunning time-lapse depicting the sun’s solar cycle, an 11-year-long period bookended by the flipping of the star’s magnetic poles. https://www.youtube.com/watch?v=l3QQQu7QLoM&t=1068s The Solar Cycle The hour-long video begins at a point in the sun’s solar cycle called the “solar minimum.” This period is relatively calm, with just the occasional burst of bright light signalling some sort of solar activity, a sunspot or solar flare, for example. The number and intensity of these bursts increases in the video until they peak near its midpoint — that’s when the cycle reaches the “solar maximum” — and then begin subsiding once again. When the SDO launched, NASA didn’t expect the spacecraft to capture this entire solar cycle — it was only designed for a five-year mission. But because it has remained functional for twice that, NASA scientists have been able to collect data on a full cycle — data they can use to predict the sun’s future magnetic activity, which could affect everything from the function of satellites to the health of astronauts. Credits: Kristin Houser | |
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| sherbPosted at 2023-03-18 00:42:21(85Wks ago) Report Permalink URL | ||
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| miokPosted at 2023-03-19 14:29:14(85Wks ago) Report Permalink URL | ||
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|  We’re About To Witness A Super-Rare Planetary Alignment In March’s Early Morning Sky  Depending on the time of year, we may view various amazing sights out in space when we gaze up into the night sky. Unfortunately, the sky has seemed relatively empty during the last month. But, as it turns out, all you have to do is know WHEN to look. The planets visible to the naked eye are now on the opposite side of the planet (the sun-facing side.) Every evening of the month, you might gaze up at the sky and be greeted with a very barren sky. Worse, Venus and Mars are quite near to one another and visible with the naked eye throughout the month, but not exactly after sunset. According to BigThink, these two planets will be so near together on March 16 that they will only be approximately three fingers wide apart at arm’s length! On March 20th, Venus will be the brightest of all, when it reaches maximum elongation. Then, on March 28, Mars, Saturn, and Venus will all be visible in the night sky, and you will be able to see Saturn pretty well if you use binoculars. Not only that, but they will fit inside a 5.3-degree circle. This close proximity of planetary trios is extremely rare. So, you may be wondering, if the planets are all hidden on the other side, how am I going to see them? The secret is to stay up late and be outdoors a few hours before dawn, or to get up early. Throughout the month of April, Jupiter, Saturn, Mars, and Venus will all be visible in the pre-dawn sky! While it may seem to be a difficult chore (staying up late or getting up early), I guarantee you that this view is well worth it. And if you like gazing at the stars and planets in space, you can’t miss out on this! Credits: BigThink, Whenthecurvaturelineup | |
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| GarthockPosted at 2023-03-19 15:28:35(85Wks ago) Report Permalink URL | ||
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| What is a quasar?  Artist’s concept of quasar J0313-1806, currently the most distant quasar known. Quasars are highly luminous objects in the early universe, thought to be powered by supermassive black holes. This illustration shows a wide accretion disk around a black hole, and depicts an extremely high-velocity wind, flowing at some 20% of light-speed, found in the vicinity of JO313-1806. View an annotated version of this image. Image via NOIRLab/ NSF/ AURA/ J. da Silva/ Keck Observatory. What is a quasar? The word quasar stands for quasi-stellar radio source. Quasars got that name because they looked starlike when astronomers first began to notice them in the late 1950s and early 60s. But quasars aren’t stars. Scientists now know they are young galaxies, located at vast distances from us, with their numbers increasing towards the edge of the visible universe. How can they be so far away and yet still visible? The answer is that quasars are extremely bright, up to 1,000 times brighter than our Milky Way galaxy. We know, therefore, that they’re highly active, emitting staggering amounts of radiation across the entire electromagnetic spectrum. Because they’re far away, we’re seeing these objects as they were when our universe was young. The oldest quasar, currently, is J0313-1806. Its distance is approximately 13.03 billion light-years, and therefore we see it as it was just 670 million years after the Big Bang. What was happening in our universe at that time to make quasars so astoundingly bright?  Here are 100 quasars identified via data from the Hyper Suprime-Cam mounted on the Subaru Telescope. The top 7 rows represent the 83 new discoveries. The bottom 2 rows represent 17 previously known quasars in the survey area. Image via NAOJ. Quasars as the centers of galaxies Astronomers now believe that quasars are the extremely luminous centers of galaxies in their infancy. After decades of intense study, we have another term for these objects: a quasar is a type of active galactic nucleus, or AGN. There are actually many different types of AGNs, each with their own tale to tell. Theoretically, the intense radiation released by an AGN powers a supermassive black hole at its center. The radiation comes from material in the accretion disk surrounding the black hole when it is superheated to millions of degrees by the intense friction generated by the particles of dust, gas and other matter in the disk colliding countless times with each other. The inward spiral of matter in a supermassive black hole’s accretion disk – that is, at the center of a quasar – is the result of particles colliding and bouncing against each other and losing momentum. That material came from the enormous clouds of gas, mainly consisting of molecular hydrogen, which filled the universe in the era shortly after the Big Bang. Thus, positioned as they were in the early universe, quasars had a vast supply of matter to feed on. As matter in a quasar/black hole’s accretion disk heats up, it generates radio waves, X-rays, ultraviolet and visible light. The quasar becomes so bright that it’s able to outshine entire galaxies. But remember … quasars are very far away. They’re so far from us that we only observe the active nucleus, or core, of the galaxy in which they reside. We see nothing of the galaxy apart from its bright center. It’s like seeing a distant car headlight at night: you have no idea of which type of car you are looking at, as everything apart from the headlight is in darkness. Seyfert galaxies On the other hand, there are galaxies which are not classed as quasars but that still have bright, active centers where we can see the rest of the galaxy. An example of this type of AGN is a Seyfert galaxy, named after the late astronomer Carl Keenan Seyfert, who was the first to identify them.  Here are 100 quasars identified via data from the Hyper Suprime-Cam mounted on the Subaru Telescope. The top 7 rows represent the 83 new discoveries. The bottom 2 rows represent 17 previously known quasars in the survey area. Image via NAOJ. Seyfert galaxies make up perhaps 10% of all the galaxies in the universe. They are not classed as quasars because they are much younger and have well-defined structures. Quasar-containing galaxies are young and formless. But just consider the amounts of energy required to illuminate an object sufficiently to make it visible in radio waves from the farthest reaches of the universe. It’s like a mariner being able to glimpse a distant lighthouse across an entire ocean. Quasars can emit up to a thousand times the energy of the combined luminosity of the 200 billion or so stars in our own Milky Way galaxy. A typical quasar is 27 trillion times brighter than our sun! Replace the sun in the sky with a quasar and its incredible luminosity would blind you instantly should you be foolhardy enough to look at it directly. If you were to place a quasar at the distance of Pluto, it would vaporize all of Earth’s oceans to steam in a fifth of a second. Galactic evolution Astronomers believe that most, if not all, large galaxies went through a so-called “quasar phase” in their youth, soon after their formation. If so, they subsided in brightness when they ran out of matter to feed the accretion disk surrounding their supermassive black holes. After this epoch, galaxies settled into quiescence, their central black holes starved of material to feed on. The black hole at the center of our own galaxy has been seen to flare up briefly, however, as passing material strays into it, releasing radio waves and X-rays. It’s conceivable that a black hole can tear apart entire stars and consume them as they cross its event horizon, the point of no return. Keep in mind, though, that our knowledge of galaxy evolution – from youthful quasar to quiescent middle-aged galaxy – is far from complete. Galaxies often provide us with exceptions, and as an example we need look no further than our own Milky Way. We now know, for example, that 3.5 million years ago there was a gigantic explosion known as a Seyfert flare at the center of our galaxy. It was apparently centered on Sagittarius A*, the Milky Way’s supermassive black hole, producing two huge lobes of superheated plasma extending some 25,000 light years from the north and south galactic poles. Scientists call these huge lobes Fermi bubbles and they are visible today at gamma and X-ray wavelengths (very high frequency electromagnetic emissions). So astronomers are still learning about the specifics of galaxy evolution.  Artist’s concept of the mind-boggling Fermi bubbles, discovered in 2010. These huge lobes extend above and below the plane of our Milky Way galaxy. They shine in gamma rays and X-rays and thus are invisible to the human eye. The graph shows how the Hubble Space Telescope was used to probe the light from a distant quasar to analyze the Fermi bubbles. A quasar’s light passed through one of these bubbles. Imprinted on that light is information about the outflow’s speed, composition, and eventually mass. Thus quasars aren’t only mysterious, they can be useful too! Image via HubbleSite. History of quasar discovery Indeed, the history of quasars hasn’t been an easy road for astronomers to follow. First discoveries in the late 1950s came from astronomers using radio telescopes. They saw starlike objects that radiated radio waves (hence quasi-stellar radio objects), but which were not visible in optical telescopes. Their resemblance to stars, their brightness and small angular diameters understandably led astronomers of the time to assume they were looking at objects within our own galaxy. However, examination of the radio spectra from these objects revealed them to be more mysterious than anyone had expected. Many early observations of quasars, including those of 3C48 and 3C273, the first two quasars to be discovered, took place in the early 1960s by British-Australian astronomer John Bolton. He and his colleagues found it puzzling that quasars were not visible in optical telescopes. They wanted to find quasars’ so-called “optical counterparts,” that is, a quasar which would be visible to their eyes in a telescope rather than only being detectable with radio instruments. Astronomers simply didn’t know at that time that quasars were extremely distant, too distant for their optical counterparts to be visible from Earth at that time, despite being intrinsically brilliant objects. But then, in 1963, astronomers Allan Sandage and Thomas A. Matthews found what they were looking for: what appeared to be a faint, blue star at the location of a known quasar. Its spectrum perplexed them. It looked like nothing they had ever seen before. They couldn’t make heads or tails of it. Then, using the 200-inch (5 m) Hale telescope, Bolton and his team observed quasar 3C273 as it passed behind the moon. These observations also let them obtain spectra. And again the spectra looked strange, showing unrecognizable emission lines. These lines tell astronomers which chemical elements are present in the object they are examining. But the quasar’s spectral lines were nonsensical, seeming to indicate elements which should not be present.  The hydrogen spectrum of quasar 3C273. The emission lines fall farther to the right, toward longer wavelengths, compared to where hydrogen emission lines would normally be located on the spectrum. They are redshifted, indicating that the quasar is located at an extreme distance from us. Image via University of Alberta.. Astronomer Maarten Schmidt – after examining the strange emission lines in the spectra of quasars – suggested that astronomers were seeing normal emission lines that were highly shifted towards the red end of the electromagnetic spectrum! And so they had their answer. The redshift was due to the quasar’s great distance. Light being stretched by the expansion of the universe during its long journey to us from the edge of the visible cosmos appears much redder. How far away are they? But if it were really true that quasars were as far away as towards the edge of the visible universe, how could they have generated such copious quantities of energy? Back in 1964, even the existence of black holes caused hot debate. Many scientists considered them nothing more than mathematical freaks, because surely they could not exist in the real universe. So the debate about the nature of quasars raged on until the 1970s when a new generation of Earth- and space-based telescopes established beyond reasonable doubt that quasars do indeed lie at vast distances, that we are seeing galaxies when they were young, that the quasar stage is a natural phase of their growth. With black holes finally being taken seriously too, astronomers could now finally model the identity of the almost incomprehensible powerhouse behind quasars: supermassive black holes consuming stupendous amounts of gas and radiating vast amounts of energy across the spectrum as a result. This model explains why quasars sit towards the edge of the visible universe and why we don’t see them closer: because quasars are young galaxies, seen not long after their formation in the early universe. The quasar: still a mystery The study of quasars, and active galactic nuclei in general, has come far, but there is much we still don’t understand. However, I believe part of our lack of understanding is a failure of imagination. It is virtually impossible to comprehend the amounts of energy generated by the black hole engines at the hearts of quasars, those monsters in the dark. It is equally hard to appreciate just how far they are from us. But that is hardly our fault: our poor simian brains are just not well-equipped to deal with such concepts. Quasars are just one example of an animal in the cosmic zoo about which one just has to accept the facts rather than try to comprehend them.  Artist’s concept of the quasar Poniua’ena, the first quasar to receive an indigenous Hawaiian name. Image via International Gemini Observatory/ NOIRLab/ NSF/ AURA/ P. Marenfeld/ UANews. Bottom line: Quasars are extremely bright and extremely distant objects. Their huge energy output is thought to be due to activity around the central supermassive black hole in young galaxies, near the edge of the observable universe. Credit: EarthSky | |
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| Jase1Posted at 2023-03-20 10:23:18(85Wks ago) Report Permalink URL | ||
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|  Finding sizeable supplies of accessible water is a key aim for teams working towards sending humans to Mars. Previous research has focused on higher latitudes, where the conditions are more suited to stable ice but also more challenging for humans (and robots). However, the recent discovery has not found ice itself at the equator – but what looks like a layer of salt covering one. Researchers from the Search for Extraterrestrial Intelligence (SETI) and the Mars Institute have detected what are known as light-toned deposits (LTDs). These deposits, detected using data from the High Resolution Imaging Science Experiment on NASA’s Mars Reconnaissance Orbiter, are signs of what they call a ‘relict glacier’. ‘What we’ve found is not ice, but a salt deposit with the detailed morphologic features of a glacier,’ said lead author Dr Pascal Lee, a planetary scientist with SETI and the Mars Institute. ‘What we think happened here is that salt formed on top of a glacier while preserving the shape of the ice below, down to details like crevasse fields and moraine bands.’ The team suggests earlier volcanic activity in the region covered the glacier in ash, pumice and lava blocks, which reacted with the water ice to form a salty crust. Over time erosion has worn away the volcanic layer, exposing the salt deposits. Similar situations have been observed on Earth. On the Altiplano – the Andean plateau – in South America, glacier ice has been protected from melting under a blanket of salts. ‘The desire to land humans at a location where they might be able to extract water ice from the ground has been pushing mission planners to consider higher latitude sites,’ said Lee. ‘But the latter environments are typically colder and more challenging for humans and robots. If there were equatorial locations where ice might be found at shallow depth, then we’d have the best of both environments – warmer conditions for human exploration and still access to ice.’  Both Nasa and China are working on manned missions to Mars. China is aiming to launch its first mission in 2033, while Nasa is aiming for the late 2030s or early 2040s. Last year the agency successfully launched its new spacecraft Orion, which it hopes will carry its Artemis III team to the Moon in 2025 – a first step towards establishing longer-term habitation and a launchpad for interplanetary exploration. Earlier this week it unveiled its new spacesuit for the mission. | |
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| Jase1Posted at 2023-03-20 13:50:43(85Wks ago) Report Permalink URL | ||
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|  The Nancy Grace Roman Space Telescope will be the next big space telescope to launch following the deployment of the latest NASA telescope, which itself was the successor to the still-active Hubble telescope. Roman’s launch will usher in "a new age for astronomy," one of the European Space Agency (ESA) scientists working on the project told Euronews Next; it will gather more data than any other NASA mission launched before, and attempt to answer some of the biggest questions in astrophysics. Scheduled to launch by 2027 at the latest, it will be able to capture "a more panoramic view of the universe and to allow more statistical studies," explained Marco Sirianni, ESA’s Science Operations Development Manager who is working on the project with NASA. While a NASA-led mission, ESA is contributing some of the technology and expertise to the mission, in return for access to the unprecedented amount of data that it will deliver. Here’s a look at what to expect from the next big NASA space telescope. It will be able to create infrared images that are 200 times larger than Hubble while providing the same rich level of detail with its similarly sized 2.4-metre diameter mirror. So while it will be able to produce "exquisite" images, the likes of which we have gotten used to from Hubble and Webb, it is mainly "going to be a telescope dedicated for surveys," said Sirianni. "In order to look for the star population in a nearby galaxy, which is very large for the field of view of Hubble, we have to stitch and do mosaics of very different shots. With Roman, we can take a picture of the full galaxy in one single shot," he says. For example, a recent “mosaic" of our neighbouring galaxy Andromeda was put together with 400 individual images taken by Hubble. Roman will be able paint the same vast picture with the same level of detail with just two images. And these much larger images means there will be an unprecedented amount of data collected. "Just to give you an idea, in 30 years of Hubble operating we have gathered something like 170 terabytes of data," explained Sirianni. "For Webb, we expect in five years to have 1,000 terabytes. And for the 5 years nominal life for Roman we expect to have 20,000 terabytes". Ultimately, it will gather data on billions of galaxies to create a "3D model of the universe". One of the goals is to test Albert Einstein’s theory of general relativity, which is well tested against the scale of our solar system for example, but less so on larger cosmological scales. Visible matter within the universe should, according to the theory, slow down the expansion of the universe, so scientists attribute the speed of expansion of the universe to a mysterious component - dark energy - which they believe makes up roughly 68 per cent of the universe. Roman will give us data that can accurately measure the position and distance of millions of galaxies and will help us to understand the expansion rate of the universe in different areas. Ultimately, the results will tell us if Einstein's theory of gravity needs modification. "If two stars align to each other, the one in front will distort and magnify the light of the star behind. And if the star in the foreground has a planet, we will see the impact of that planet on the light of the star behind it," said Sirianni. Given Roman will count billions of stars, it will provide a "very good census of how many stars will have exoplanets," he added. Not only will it spot new exoplanets, but Roman will carry a second main instrument - called a coronagraph - which aims to image exoplanets that are close to their parent star. "This is a very difficult technique because the starlight has to be suppressed - it is orders of magnitude brighter than the objects that you want to study, the nearby planet," said Sirianni. The coronagraph on Roman will attempt to directly capture large planets similar to Jupiter, conducting live corrections to improve image quality. It will be a demonstration instrument - and if it proves to work, it will form the baseline for the technology to be used on future space observatories that will be attempting to directly image Earth-like planets in the habitable zone of their parent star. The space agency will provide "star trackers," small telescopes in the spacecraft that constantly determine its position in the sky by tracking stars. Then it will provide batteries to help power the spacecraft before its solar panels are deployed. And finally, it will also supply detectors for the coronagraph onboard. Furthermore, ESA’s own mission to measure the expansion of the universe and reveal more about dark energy is launching this summer. The Euclid space telescope will gather the information that will then be complementary to the data gathered by Roman. Like ESA’s contribution to Roman, NASA is making small contributions to the Euclid mission too. | |
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| hayzee56Posted at 2023-03-20 14:02:57(85Wks ago) Report Permalink URL | ||
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| Wow, if it weren't for the Space Shuttle the Hubble ST would have been gone years ago and the JWST basically only just started transmitting data and they have more planned. Can't wait to find out what they discover at a later date. | |
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| Jase1Posted at 2023-03-20 15:47:59(85Wks ago) Report Permalink URL | ||
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|  Under a SpaceWERX Small Business Innovation Research contract, Arkisys, Novawurks, Motiv Space Systems, Qediq, iBoss and Texas A&M University will demonstrate how they would assemble a three-axis stabilized satellite with the robotic arm on the Arkisys Port Module. “This effort expands the overall services we have created to include the ability to utilize the robotic arm on top of the Port Module to assemble a separable space platform and then release it in orbit,” Dave Barnhart, Arkisys CEO and co-founder, told SpaceNews. “Through the unique SBIR process from U.S. Space Force and SpaceWERX, we will address using resources in space to create new platforms or modify them on the fly,” Talbot Jaeger, Novawurks chief technology officer, said in a statement. “The Port will demonstrate a platform that can create a space system from parts into an operational element.” For example, operation of a robotic arm imparts momentum on a space platform. Texas A&M Engineering Experiment Station will help the Arkisys-led team figure out how to keep the platform stable. “The ability to assemble a functional satellite off of another platform is something that will open up not just Earth-orbit markets and on-the-fly changes to existing satellites, but on-demand satellites for lunar or Martian exploration,” Robert Ambrose, director of space and robotics Initiatives at the Texas A&M Engineering Experiment Station, said in a statement. “This is incredibly exciting for us as we are developing platforms to validate and demonstrate higher fidelity robotics on orbit, to build, assemble, repair and operate .” For the demonstration, iBoss Space of Germany and Novawurks will supply the hardware and software interfaces. Motiv is providing the robotic arm. Qediq is helping Arkisys develop and build the Applique, a universal interface adapter to connect spacecraft payloads. Arkisys was founded in 2014 to develop the Port, a platform in low-Earth orbit for prototyping, testing, assembly and integration. The Port also is designed to serve as a destination for orbital transfer vehicles. | |
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| BeowulfPosted at 2023-03-20 17:50:01(85Wks ago) Report Permalink URL | ||
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|  A bright foreground star isn’t enough to distract from the grandeur of the galaxy UGC 3855, captured here by the NASA/ESA Hubble Space Telescope. While this foreground star is incredibly bright to Hubble’s eye, it does not outshine the details of the background galaxy. Many young blue stars are sprinkled throughout the circular patterns of UGC 3855’s arms, contrasted and complemented by dark lanes of dust also following the spiral structure. A glancing look at UGC 3855 may only leave you with an impression of the galaxy, but spare a moment longer and the intricacies of the galaxy begin to emerge. Located in the constellation of Lynx , UGC 3855 is a cosmic beauty to behold. Credit: ESA/Hubble & NASA, J. Walsh & Beowulf | |
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| Jase1Posted at 2023-03-21 10:38:07(85Wks ago) Report Permalink URL | ||
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|  This newest image was part of an initiative to explore debris left behind following Type III supernovas. These violent stellar explosions occur when a star rapidly collapses in on itself, sending debris flying through the universe around it. This galaxy was home to a supernova back in 2004. Astronomers used Hubble to observe the spiral galaxy back then to learn more about the aftermath of supernovas. The galaxy Hubble observed is considered an irregular spiral galaxy because it doesn’t fit the look of a traditional spiral, having no defined structure or shape. NGC 5486 is located roughly 110 million light-years from Earth, within the constellation Ursa Major. Astronomers believe the spiral galaxy’s appearance was most likely altered and distorted by the gravity of a larger neighbouring galaxy.  Other images that Hubble has captured showcase beautiful vistas like a galactic seascape called JO201. Those images offer similarly beautiful glimpses of what Hubble is capable of capturing, and together with this spiral galaxy image, help highlight the various parts of our universe. As the telescope continues to orbit our planet, its trajectory is also finding interference from other satellites and spacecraft, bringing many to call for Hubble’s orbit to be pushed higher to help avoid such occurrences. Unfortunately, NASA and SpaceX have yet to reveal anything regarding their talks to continue support for Hubble throughout the coming years. | |
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| Jase1Posted at 2023-03-22 09:56:12(84Wks ago) Report Permalink URL | ||
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|  Something strange is happening beneath our feet. Over the years, seismic studies have detected a number of anomalies happening in the area between the Earth’s core and mantle, which were believed to be the result of processes in the mantle. A new study published on Wednesday in Nature suggests this activity may in fact be related to the Earth’s core. As the authors explain in the study, the boundary between the Earth’s and mantle represents an interface between the solid silicate mantle and the liquid metallic outer core, and the structure and dynamics in this region are fundamental for understanding heat and material transfer in our planet. Seismic imaging has allowed scientists to discover fine-scale structures at the boundary between the Earth's core and mantle. These “anomalies” are characterized by differences in velocity and density compared to the surrounding normal mantle or core region. This study specifically focused on the Earth’s outer core, located about 3000 km below the surface. The region is made up of thick liquid iron alloy, which has a big impact on the habitability of the Earth’s surface and the creation of its magnetic field. Obviously, researchers can’t access the actual core, but can conduct research in similar conditions in a lab––which is what the study’s authors did. “We conducted experiments to see what happens when we combine iron-hydrogen alloy liquid with silicon under high pressure and high temperature conditions, like those found in the outer core,” One of the study’s authors, geoscientist Suyu Fu from Arizona State University, wrote in an email to Motherboard. “We discovered that silicon-rich crystals form in the iron metal liquid (or silicon-rich snow), and they are lighter than the outer core liquid, causing them to rise to the boundary between the metallic core and the rocky mantle (rather than sink).” Fu noted that this process can create a pile of silicon-rich snow, which can help us understand some puzzling structures found at the Earth's core-mantle boundary. “Our study sheds light on the causes of two distinct seismic wave velocity anomalies at the Earth's core-mantle boundary, namely ultra-slow zones on the mantle side and the core rigidity zone on the core side,” he wrote. “While the slow zones were previously believed to be linked mainly to mantle processes, our research suggests that some of them may be generated by processes occurring in the outer core. For the core rigidity zone, some researchers have hypothesized that the precipitation of light elements in the outer core might be responsible. We found evidence that the phenomenon of silicon "snowing" could be behind the observed core rigidity zone.” Despite existing beneath our feet, there's a lot we still don't know about the Earth's insides, and especially the core. Just last month, scientists published a study suggesting that the core has in fact stopped and may be reversing direction, which would explain a number of cyclical phenomena. And more recently, scientists discovered that there is an entire zone of the Earth located 100 miles below the surface that has eluded detection until now. The new findings have implications for understanding the chemistry of the deep Earth. As Fu explained, research has revealed that some volcanic rocks found on ocean islands, such as Hawaii, contain a chemical signature similar to that of the Earth's core. “Our study suggests that if silicon-rich crystals from the Earth's core mix with mantle silicates to form these ultra-low velocity zones, they could provide a source for the core-like chemical signatures found in the volcanic rocks.” | |
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| BeowulfPosted at 2023-03-22 13:50:34(84Wks ago) Report Permalink URL | ||
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|  In the forests of the night lies a barred spiral galaxy called NGC 3583, imaged here by the NASA/ESA Hubble Space Telescope. This is a barred spiral galaxy with two arms that twist out into the Universe. This galaxy is located 98 million light-years away from the Milky Way. Two supernovae exploded in this galaxy, one in 1975 and another, more recently, in 2015. There are a few different ways that supernova can form. In the case of these two supernovae, the explosions evolved from two independent binary star systems in which the stellar remnant of a Sun-like star, known as a white dwarf, was collecting material from its companion star. Feeding off of its partner, the white dwarf gorged on the material until it reached a maximum mass. At this point, the star collapsed inward before exploding outward in a brilliant supernova. Two of these events were spotted in NGC 3583, and though not visible in this picture of the week, we can still marvel at the galaxy’s fearful symmetry. Credit: ESA/Hubble & NASA, A. Riess et al. & Beowulf | |
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| GarthockPosted at 2023-03-22 14:47:42(84Wks ago) Report Permalink URL | ||
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| NASA unveils plan for Artemis 'base camp' on the moon beyond 2024  An artist's depiction of work on the moon as part of the Artemis program. (Image credit: NASA) NASA is forging ahead with its Artemis program to land humans on the moon by 2024, but the agency has also just offered its first plan for what a U.S. lunar presence may look like after that milestone. The new plan comes from a 13-page report submitted on April 2 to the National Space Council, an advisory group to President Donald Trump chaired by Vice President Mike Pence. Much of the report, titled "NASA’s Plan for Sustained Lunar Exploration and Development," summarizes the vision NASA has laid out for justifying and accomplishing the 2024 moon landing. But the report also looks farther out to focus on what a long-term presence on the moon and in lunar orbit would permit the U.S. to accomplish. "After 20 years of continuously living in low-Earth orbit, we're now ready for the next great challenge of space exploration — the development of a sustained presence on and around the moon," NASA Administrator Jim Bridenstine said in a statement released with the report. "For years to come, Artemis will serve as our North Star as we continue to work toward even greater exploration of the moon, where we will demonstrate key elements needed for the first human mission to Mars." Artemis Base Camp The star of the report is what NASA has dubbed Artemis Base Camp, meant to be a long-term foothold for lunar exploration, perhaps in Shackleton Crater at the moon's south pole. According to the document, Artemis Base Camp itself would be a lunar foundation surface habitat that could host four astronauts at the south pole for visits of perhaps a week. In the long term, the facility would also require infrastructure for power, waste disposal and communications, as well as radiation shielding and a landing pad. The base could also be a site for testing new techniques for dealing with pesky lunar dust and the long, cold lunar nights, turning local materials into resources like water, and developing new power and construction technologies.  NASA's Artemis program aims to roll out a base camp on the moon in stages using an orbiting Gateway station, landers, rovers and habitats as seen in this timeline illustration. (Image credit: NASA) Artemis Base Camp would be accompanied and supported by two mobility systems: a lunar terrain vehicle to facilitate astronaut movement across the surface and a habitable mobility platform that could support trips away from base for up to 45 days. (NASA is currently envisioning Mars surface missions as lasting just 30 to 45 days to reduce risks, according to the same document.) "Mobility is a major part of the Artemis Base Camp," the report reads. "Robust mobility systems will be needed to explore and develop the moon. The same is true for Mars, making the habitable mobility platform a particularly important element as we will need a similar type of vehicle to explore the Red Planet." Gateway to Mars The report also outlines a plan to use the moon-orbiting waystation dubbed the Gateway as a site for Mars analog missions. These practice missions could play out as a team of four astronauts living on the Gateway for several months, to mimic the duration of a journey to Mars, then a landing crew of two visiting the moon's surface, then another long orbital stay to fill out the mission's timeline. "These missions will be by far the longest duration human deep-space missions in history," the report states. "They will be the first operational tests of the readiness of our long-duration deep space systems, and of the split crew operations that are vital to our approach for the first human Mars mission." But the long-term vision for Artemis includes plenty of moon-specific science as well as preparing for Mars exploration. "In time, Artemis Base Camp might also include a hopper that could deliver science and technology payloads all over the moon and which could be operated by crew at Artemis Base Camp and refueled using locally sourced propellant," the report reads. "A lunar far-side radio telescope could also be remotely emplaced and operated from Artemis Base Camp — a sort of backyard radio-telescope at our first encampment on the moon." | |
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| BeowulfPosted at 2023-03-22 17:35:02(84Wks ago) Report Permalink URL | ||
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|  This peculiar galaxy, beautifully streaked with tendrils of reddish dust, is captured here in wonderful detail by the NASA/ESA Hubble Space Telescope. The galaxy is known as NGC 1022, and is officially classified as a barred spiral galaxy. You can just about make out the bar of stars in the centre of the galaxy in this image, with swirling arms emerging from its ends. This bar is much less prominent than in some of the galaxy’s barred cousins and gives the galaxy a rather squat appearance; but the lanes of dust that swirl throughout its disc ensure it is no less beautiful.  Hubble observed this image as part of a study into one of the Universe’s most notorious residents: black holes. These are fundamental components of galaxies, and are thought to lurk at the hearts of many — if not all — spirals. In fact, they may have quite a large influence over their cosmic homes. Studies suggest that the mass of the black hole sitting at a galaxy’s centre is linked with the larger-scale properties of the galaxy itself. However, in order to learn more, we need observational data of a wider and more diverse range of galaxies — something Hubble’s study aims to provide. Credit: ESA/Hubble & NASA, A. Seth & Beowulf | |
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| Jase1Posted at 2023-03-23 09:42:44(84Wks ago) Report Permalink URL | ||
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|  Does the Universe have an edge? What is outside the Universe? Does such a question even make sense? By Govert Schilling Published: Tuesday, 21 March 2023 at 12:00 am It’s one of the most perplexing questions in cosmology: does our Universe have an edge? If you keep travelling through space in an imaginary faster-than-light spaceship, would you ever arrive at some boundary, unable to go any further? And if the Universe does have an edge, what lies beyond it? It’s all very hard to imagine. Then again, an infinite Universe is just as difficult to wrap your head around. After all, there must be something that space is expanding into, right?  Let’s start with a related but easier-to-grasp concept: our Universe has an apparent edge, called the cosmological horizon. The light emitted right after the Big Bang has been travelling for 13.8 billion years through space. This means we can only see the Universe up to a current distance corresponding to a light-travel time of 13.8 billion years. Thanks to the expansion of space, this so-called co-moving distance is approximately 45 billion lightyears, and anything beyond this limit is unobservable to us because not enough time has elapsed since the birth of the Universe for light from these remote regions to reach our telescopes. But, just like the familiar horizon seen by sailors on the ocean, this cosmological horizon is not some real, physical boundary. And as the ocean stretches beyond the sailor’s horizon, so too does space stretch beyond our observable Universe.  There’s no reason why there can’t be galaxies at these extremely large distances; they’re just invisible to us, no matter how powerful our telescopes are. But knowing the Universe goes on beyond 45 billion lightyears still doesn’t tell us whether it’s finite or infinite. One thing’s for sure: the Universe does not have an edge. There’s no physical boundary – no wall, no border, no fence around the edges of the cosmos. This doesn’t necessarily mean that the Universe is infinitely large though. In principle, we could live in a finite Universe, provided that three-dimensional empty space is geometrically curved in a particular way – a distinct possibility according to Albert Einstein’s theory of general relativity. If the Universe has what’s known as positive curvature, it would be like the curved surface of a beach ball, but rather than a 2D surface, it’s 3D space.  It is finite – if you were living in this flattened version of the cosmos, you wouldn’t need an infinite amount of paint to cover your 2D Universe – yet there is no boundary or edge to the surface itself. In contrast, a negatively curved Universe would be a higher-dimensional version of a Pringle – curving upwards along one axis and downwards along the other – while a flat Universe would resemble a piece of paper. Both of these versions would stretch out infinitely. Cosmologists have tried to measure the large-scale curvature of space over the past few decades, and the most recent results combined with theoretical arguments seem to indicate that we live in a geometrically flat Universe. On the one hand, that’s convenient as our brains aren’t very good at imagining large-scale space curvature – even here we’ve had to describe our 3D Universe in 2D terms.  On the other hand, this means that our Universe is infinitely large, and that our observable Universe – the part within our cosmological horizon – is only an infinitesimally small fraction of an unimaginably large whole. In case you were wondering how our infinite, boundless Universe is able to expand, return once again to our 2D analogy. If you saw the grid size on a piece of graph paper growing, you would justifiably conclude that the paper is expanding. If the paper was so large that you couldn’t see the edge, you’d still draw the same conclusion, even though the piece of paper could also be infinitely large. The same is true for an infinite Universe. After all, infinity times two is still infinity! | |
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| BeowulfPosted at 2023-03-23 14:09:40(84Wks ago) Report Permalink URL | ||
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|  This is an illustration of the supermassive black hole located in the middle of the very dense galaxy M60-UCD1. It weighs as much as 21 million times the mass of our Sun. Lying about 50 million light-years away, M60-UCD1 is a tiny galaxy with a diameter of 300 light-years — just 1/500th of the diameter of the Milky Way! Despite its size it is pretty crowded, containing some 140 million stars. Because no light can escape from the black hole, it appears simply in silhouette against the starry background. The black hole’s intense gravitational field warps the light of the background stars to form ring-like images just outside the dark edges of the black hole’s event horizon. Combined observations by the NASA/ESA Hubble Space Telescope and NASA’s Gemini North telescope determined the presence of the black hole inside M60-UCD1. Credit: NASA, ESA, D. Coe, G. Bacon & Beowulf | |
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| Jase1Posted at 2023-03-23 15:00:50(84Wks ago) Report Permalink URL | ||
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| James Webb telescope detects dust storm on distant world  Artwork of VHS 1256b: The planet takes about 10,000 years to go around its two parent stars A raging dust storm has been observed on a planet outside our Solar System for the first time. It was detected on the exoplanet known as VHS 1256b, which is about 40 light-years from Earth. It took the remarkable capabilities of the new James Webb Space Telescope (JWST) to make the discovery. The dust particles are silicates - small grains comprising silicon and oxygen, which form the basis of most rocky minerals. But the storm detected by Webb isn't quite the same phenomenon you would get in an arid, desert region on our planet. It's more of a rocky mist. "It's kind of like if you took sand grains, but much finer. We're talking silicate grains the size of smoke particles," explained Prof Beth Biller from the University of Edinburgh and the Royal Observatory Edinburgh, UK. "That's what the clouds on VHS 1256b would be like, but a lot hotter. This planet is a hot, young object. The cloud-top temperature is maybe similar to the temperature of a candle flame," she told BBC News. VHS 1256b was first identified by the UK-developed Vista telescope in Chile in 2015. It's what's termed a "super Jupiter" - a planet similar to the gas giant in our own Solar System, but a lot bigger, perhaps 12 to 18 times the mass. It circles a couple of stars at great distance - about four times the distance that Pluto is from our Sun. Earlier observations of VHS 1256b showed it to be red-looking, hinting that it might have dust in its atmosphere. The Webb study confirms it. "It's fascinating because it illustrates how different clouds on another planet can be from the water vapour clouds we are familiar with on the Earth," said Prof Biller. "We see carbon monoxide (CO) and methane in the atmosphere, which is indicative of it being hot and turbulent, with material being drawn up from deep. "There are probably multiple layers of silicate grains. The ones that we're seeing are some of the very, very fine grains that are higher up in the atmosphere, but there may be bigger grains deeper down in the atmosphere." | |
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| BeowulfPosted at 2023-03-24 05:04:12(84Wks ago) Report Permalink URL | ||
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|  This Picture of the Week shows a beautiful meeting between the Swedish–ESO Submillimetre Telescope (SEST) and the Milky Way, apparently almost touching each other. This shot was taken at ESO’s La Silla Observatory, located on the outskirts of the Chilean Atacama Desert, at an altitude of 2400 metres. Light and darkness shape the Milky Way as it stretches across the night sky. The dark patches are dust clouds blocking the light behind them, coming from millions of stars in the central region of our galaxy. SEST was built on behalf of the Swedish Natural Science Research Council (NFR) and ESO in 1987. It is a 15-m radio telescope, and it was the only large sub-millimetre telescope in the southern hemisphere at the time of first light. In 2003, the telescope was decommissioned as it was superseded by the Atacama Pathfinder EXperiment telescope (APEX) and the Atacama Large Millimeter/submillimeter Array (ALMA) further north in Chile. Over the years SEST has observed a wide range of astronomical objects, from comets to stellar nurseries and galaxies. Credit: ESO/A. Ghizzi Panizza & Beowulf | |
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| Jase1Posted at 2023-03-24 20:13:30(84Wks ago) Report Permalink URL | ||
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|  NASA’s Webb Confirms Its First Exoplanett - transit light curve A whole new world! 41 light-years away is the small, rocky planet LHS 475 b. At 99% of Earth’s diameter, it’s almost exactly the same size as our home world. This marks the first time researchers have used the Webb telescope to confirm an exoplanet. NASA’s TESS mission hinted at the planet’s existence, making it a target of interest for Webb. Webb’s NIRSpec instrument then captured the planet easily and clearly with just 2 transit observations. Although Webb data definitively tells us that LHS 475 b is a small rocky world, the existence and composition of its atmosphere is a mystery. The planet is a few hundred degrees warmer than Earth and very close to its star, completing an orbit in just 2 days. However, its red dwarf star is much cooler than our Sun, so scientists theorize an atmosphere is still possible. Additional follow-up observations are scheduled this summer. Learn more about this exciting new discovery: https://www.nasa.gov/feature/goddard/2023/nasa-s-webb-confirms-its-first-exoplanet Credits: Illustration - NASA, ESA, CSA, L. Hustak (STScI); Science - K. Stevenson, J. Lustig-Yaeger, E. May (Johns Hopkins University Applied Physics Laboratory), G. Fu (Johns Hopkins University), and S. Moran (University of Arizona) In this image: How do researchers spot a distant planet? By observing the changes in light as it orbits its star. A light curve from NASA’s James Webb Space Telescope’s Near-Infrared Spectrograph (NIRSpec) shows the change in brightness from the LHS 475 star system over time as the planet transited the star on August 31, 2022. LHS 475 b is a rocky, Earth-sized exoplanet that orbits a red dwarf star roughly 41 light-years away, in the constellation Octans. The planet is extremely close to its star, completing one orbit in two Earth-days. The planet’s confirmation was made possible by Webb’s data. Image description: Graphic titled “Rocky Exoplanet LHS 475 b Transit Light Curve, NIRSpec Bright Object Time-Series Spectroscopy.” Behind the graph is an illustration of the planet and its star. The graph, or spectrum, shows the change in relative brightness of the star-planet system between 3:00 p.m. and 6:00 p.m. in Baltimore, Maryland, on August 31, 2022. The spectrum shows that the brightness of the system remains steady until the planet begins to transit the star. It then decreases, representing when the planet is directly in front of the star. The brightness increases again when the planet is no longer blocking the star, at which point it levels out. The graph shows data in purple circles, which chart measurements before, during, and after the transit. Data form a U-shaped valley of low brightness labeled “Starlight blocked by the planet” at 5 p.m. This dip cuts into a flat plain of high brightness labeled “Starlight,” which starts before the U-shaped dip, and resumes after the dip. | |
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| Jase1Posted at 2023-03-25 18:06:19(84Wks ago) Report Permalink URL | ||
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|  A stunning lineup of five planets will decorate the night sky Night sky lovers can typically spot a smattering of a few planets, but in late March, a stunning visual takes shape when five planets line up beneath the moon in a display sometimes called a planetary parade or alignment. Onlookers will be able to catch the best glimpse of the alignment — which will include Mercury, Venus, Mars, Jupiter and Uranus — on Tuesday evening, just after sunset. Much of the display will become visible on Friday and will continue to be so over the next couple of weeks, according to Cameron Hummels, a computational astrophysicist at the California Institute of Technology. Alignments such as this one appear every few years or so, Hummels said, and much of it will be visible to the naked eye, even in urban areas with significant light pollution. And it can be spotted across the Northern and Southern hemispheres. The arrangement will be visible just underneath the crescent moon. To spot the display, Hummels recommended heading out to a place with a good view of the western horizon just after sunset, when streaks of the colorful sunset still remain and the sky has turned dark blue but not yet black. (Tip: Those living far to the north should look slightly southwest, while those in the Southern Hemisphere should gaze northwest, Hummels said.) The easiest planet to spot will be Venus, often referred to as the "evening star," because it's the brightest object in the night sky apart from the moon. Uranus will appear close to Venus, though it may be difficult to pick out the distant planet without binoculars or a telescope unless you're viewing from a prime location with no light pollution. Beneath Venus and Uranus will be Jupiter and Mercury, hovering just above the horizon. Mercury may also be difficult to catch without special equipment, as the sun's glare can blot out the planet. But to careful observers, both planets will be visible for about 20 to 30 minutes after sunset, Hummels said. Topping off the planetary parade will be Mars, sitting in a straight line up from Jupiter, Mercury, Venus, Uranus and the moon. It's easy to pick out because of its signature orange tint, Hummels added. The planets will all appear "kind of like pearls on a necklace" across the night sky, Hummels said.  Venus and Jupiter appear exceptionally close to one another in an artist's rendering. The entire alignment will cover just about 70 degrees of the sky. Hummels said one method for measuring degrees in the sky is to use your thumb or closed fist, extended away from your body. A fist at arm's length will cover about 10 degrees, while a thumb covers about 1 degree. What does this mean? A planetary alignment of this kind may show up every few years, but it is possible to catch planets all together in an even smaller patch of the sky — those occurrences are just more rare. One alignment last June, for example, was the first of its kind since 2004. The event included all five planets that can typically be seen with the naked eye — Mercury, Venus, Mars, Jupiter and Saturn. Hummels said not to assign too much significance to a planetary alignment. "It's kind of like when your car's odometer shows a bunch of numbers — like it reaches 44,444," he said. "It's cool and unusual. It just doesn't really mean anything." Fascinating celestial phenomena often decorate the night sky, he added, such as when Jupiter and Venus appeared within half a degree of each other this month. On October 14, sky watchers can expect to see a "ring of fire" eclipse. And, in April 2024, a total solar eclipse will blot out the sun midday for many in the United States. | |
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