Astronomy

Questions about Hubble's brand new view of an interstellar comet (video)

Questions about Hubble's brand new view of an interstellar comet (video)


We are searching data for your request:

Forums and discussions:
Manuals and reference books:
Data from registers:
Wait the end of the search in all databases.
Upon completion, a link will appear to access the found materials.

This GIF is made (via giphy.com) from the new NASA Goddard video Hubble's New Image of Interstellar Object and if I understand correctly many (if not all) of these frames are from https://archive.stsci.edu/proposal_search.php?mission=hst&id=16009 (from this answer).

I have some questions about this set of images. I've plotted the start times below.

  1. There are four groups that last about 45 minutes, each followed by a break of either 45 minutes or 90+45 minutes, is this related to the HST's orbit?
  2. I notice a slow rotation of the star tracks over the duration of the roughly seven hours of data, it looks like roughly 20 degrees, (see GIF or the individual images) and I can't figure that out at all. Is it a rotation of the HST around its own axis?
  3. Individual preview images (example) appear to be rhomboidal rather than square, why?


TL;DR version, Yes, yes, distortion. In more detail:

  1. HST's orbit is approx. 90 minutes so this will cause the breaks. Some more information is given in the Orbital Constraints section of the Cycle 27 guide for proposers.
  2. Since HST is having to move to track the moving comet to keep it in the (small) field of view of the instruments, it will likely need to roll the spacecraft. This is to keep suitable guide stars in the Fine Guidance Sensors, to keep the Sun on the solar panels for power and to keep the pointing constraints of not looking to close to the Sun, Moon or Earth satisfied. These are discussed in more detail in the Orientation and Roll constraints section of the primer/guide for proposers mentioned earlier.
  3. This is due to the geometric distortion of the optics in UV/Visible (UVIS) channel of the WFC3 instrument as described in more detail in this section of the WFC3 Instrument Handbook,

Space Hubble Telescope News

In 1977, NASA's Voyager 1 and 2 spacecraft began their pioneering journey across the solar system to visit the giant outer planets. Now, the Voyagers are hurtling through unexplored territory on their road trip beyond our solar system. Along the way, they are measuring the interstellar medium, the mysterious environment between stars that is filled with the debris from long-dead stars. NASA's Hubble Space Telescope is providing the road map, by measuring the material along the probes' trajectories as they move through space. Hubble finds a rich, complex interstellar ecology, containing multiple clouds of hydrogen, laced with other elements. Hubble data, combined with the Voyagers, have also provided new insights into how our sun travels through interstellar space. (More at Hubble Site)

Robby

The News Robot

Hubble Detects 'Exocomets' Taking the Plunge into a Young Star

Interstellar forecast for a nearby star: Raining comets! The comets are plunging into the star HD 172555, which resides 95 light-years from Earth. The comets were not seen directly around the star. Astronomers inferred their presence when they used NASA's Hubble Space Telescope to detect gas that is likely the vaporized remnants of their icy nuclei.

The presence of these doomed comets provides circumstantial evidence for "gravitational stirring" by an unseen Jupiter-size planet, where comets deflected by the massive object's gravity are catapulted into the star. These events also provide new insights into the past and present activity of comets in our solar system. It's a mechanism where infalling comets could have transported water to Earth and the other inner planets of our solar system. HD 172555 represents the third extrasolar system where astronomers have detected doomed, wayward comets. All of these systems are young, under 40 million years old. (More at Hubble Site)

Robby

The News Robot

Hubble Captures 'Shadow Play' Caused by Possible Planet

Eerie mysteries in the universe can be betrayed by simple shadows. The wonder of a solar eclipse is produced by the moon's shadow, and over 1,000 planets around other stars have been cataloged by the shadow they cast when passing in front of their parent star. Astronomers were surprised to see a huge shadow sweeping across a disk of dust and gas encircling a nearby, young star. They have a bird's-eye view of the disk, because it is tilted face-on to Earth, and the shadow sweeps around the disk like the hands moving around a clock. But, unlike the hands of a clock, the shadow takes 16 years to make one rotation.

Hubble has 18 years' worth of observations of the star, called TW Hydrae. Therefore, astronomers could assemble a time-lapse movie of the shadow's rotation. Explaining it is another story. Astronomers think that an unseen planet in the disk is doing some heavy lifting by gravitationally pulling on material near the star and warping the inner part of the disk. The twisted, misaligned inner disk is casting its shadow across the surface of the outer disk. TW Hydrae resides 192 light-years away and is roughly 8 million years old. (More at Hubble Site)

Robby

The News Robot

'Our Place In Space:' Astronomy and Art Combine in Brand New Hubble-Inspired Exhibition

Since the dawn of civilization, we have gazed into the night sky and attempted to make sense of what we saw there, asking questions such as: Where do we come from? What is our place in the universe? And are we alone? As we ask those questions today and new technology expands our horizons further into space, our yearning for their answers only grows. Since its launch in 1990, NASA's Hubble Space Telescope has continued this quest for answers while orbiting Earth every 90 minutes. Hubble has not only made countless new astronomical discoveries, but also brought astronomy to the public eye, satisfying our curiosity, sparking our imaginations, and greatly impacting culture, society, and art.

A new traveling exhibition, "Our Place in Space" features iconic Hubble images. It presents not only a breathtaking pictorial journey through our solar system and to the edges of the known universe, but also Hubble-inspired works by selected Italian artists. By seamlessly integrating perspectives from both artists and astronomers, the exhibition will inspire visitors to think deeply about how humanity fits into the grand scheme of the universe. Before moving to other venues, the exhibition will be on display from February 1 to April 17, 2017, in the Istituto Veneto di Science, Lettere ed Arti, Palazzo Cavalli Franchetti, on the banks of the Grand Canal in Venice, Italy. For more information about the traveling exhibition and Hubble, visit: http://www.spacetelescope.org/news/heic1701. (More at Hubble Site)

Robby

The News Robot

Dr. Margaret Meixner and Dr. Marc Postman Promoted to STScI Distinguished Astronomers

The Space Telescope Science Institute (STScI) in Baltimore, Maryland, has appointed Dr. Margaret Meixner and Dr. Marc Postman to the position of STScI Distinguished Astronomer. Distinguished Astronomer is the highest level of appointment on the tenure track at STScI and represents a rank commensurate with the highest level of professorial appointments at major universities.

Meixner's promotion recognizes her long-term contributions to research and service at STScI. She has led international teams to study the life cycle of dust in the Magellanic Clouds using the Hubble, Spitzer and Herschel space telescopes. Postman is being recognized for his long-term contributions to the study of the formation and evolution of galaxies and clusters of galaxies. He has led important research to determine how the environments of galaxies determine their shapes and how the most massive galaxies evolve. (More at Hubble Site)

Robby

The News Robot

Hubble Witnesses Massive Comet-Like Object Pollute Atmosphere of a White Dwarf

Astronomers have found the best evidence yet of the remains of a comet-like object scattered around a burned-out star. They used NASA's Hubble Space Telescope to detect the debris, which has polluted the atmosphere of a compact star known as a white dwarf. The icy object, which has been ripped apart, is similar to Halley's Comet in chemical composition, but it is 100,000 times more massive and has a much higher amount of water. It is also rich in the elements essential for life, including nitrogen, carbon, oxygen, and sulfur. These findings are evidence for a belt of comet-like bodies similar to our solar system's Kuiper Belt orbiting the white dwarf. This is the first evidence of comet-like material polluting a white dwarf's atmosphere. The results also suggest the presence of unseen, surviving planets around the burned-out star. (More at Hubble Site)

Robby

The News Robot

NASA Telescope Reveals Largest Batch of Earth-Size, Habitable-Zone Planets Around Single Star

NASA's Spitzer Space Telescope has revealed the first known system of seven Earth-size planets around a single star. Three of these planets are located in an area called the habitable zone, where liquid water is most likely to thrive on a rocky planet. The system sets a new record for the greatest number of habitable zone planets found outside our solar system. Any of these seven planets could have liquid water, the key to life as we know it. The exoplanet system is called TRAPPIST-1 and is only 40 light-years away. Following up on the Spitzer discovery, NASA's Hubble Space Telescope has initiated the screening of four of the planets, including the three inside the habitable zone. These observations aim at assessing the presence of puffy, hydrogen-dominated atmospheres, typical for gaseous worlds like Neptune, around these planets. In May 2016, the Hubble team observed the two innermost planets and found no evidence for such puffy atmospheres. This finding strengthened the case that the planets closest to the star are terrestrial in nature. Astronomers plan follow-up studies using NASA's upcoming James Webb Space Telescope, scheduled to launch in 2018. With much greater sensitivity, Webb will be able to detect the chemical fingerprints of water, methane, oxygen, ozone, and other components of a planet's atmosphere. Webb also will analyze planets' temperatures and surface pressures — key factors in assessing their habitability.

For illustrations and more information about the TRAPPIST-1 system, visit: https://exoplanets.nasa.gov (More at Hubble Site)

Robby

The News Robot

The Dawn of a New Era for Supernova 1987A

In February 1987, on a mountaintop in Chile, telescope operator Oscar Duhalde stood outside the observatory at Las Campanas and looked up at the clear night sky. There, in a hazy-looking patch of brightness in the sky — the Large Magellanic Cloud (LMC), a neighboring galaxy - was a bright star he hadn't noticed before.

That same night, Canadian astronomer Ian Shelton was at Las Campanas observing stars in the Large Magellanic Cloud. As Shelton was studying a photographic plate of the LMC later that night, he noticed a bright object that he initially thought was a defect in the plate. When he showed the plate to other astronomers at the observatory, he realized the object was the light from a supernova. Duhalde announced that he saw the object too in the night sky. The object turned out to be Supernova 1987A, the closest exploding star observed in 400 years. Shelton had to notify the astronomical community of his discovery. There was no Internet in 1987, so the astronomer scrambled down the mountain to the nearest town and sent a message to the International Astronomical Union's Bureau for Astronomical Telegrams, a clearing house for announcing astronomical discoveries.

Since that finding, an armada of telescopes, including the Hubble Space Telescope, has studied the supernova. Hubble wasn't even in space when SN 1987A was found. The supernova, however, was one of the first objects Hubble observed after its launch in 1990. Hubble has continued to monitor the exploded star for nearly 30 years, yielding insight into the messy aftermath of a star's violent self-destruction. Hubble has given astronomers a ring-side seat to watch the brightening of a ring around the dead star as the supernova blast wave slammed into it. (More at Hubble Site)


Hubble solves cosmic 'whodunit' with interstellar forensics

On the outskirts of our galaxy, a cosmic tug-of-war is unfolding-and only NASA's Hubble Space Telescope can see who's winning.

The players are two dwarf galaxies, the Large Magellanic Cloud and the Small Magellanic Cloud, both of which orbit our own Milky Way Galaxy. But as they go around the Milky Way, they are also orbiting each other. Each one tugs at the other, and one of them has pulled out a huge cloud of gas from its companion.

Called the Leading Arm, this arching collection of gas connects the Magellanic Clouds to the Milky Way. Roughly half the size of our galaxy, this structure is thought to be about 1 or 2 billion years old. Its name comes from the fact that it's leading the motion of the Magellanic Clouds.

The enormous concentration of gas is being devoured by the Milky Way and feeding new star birth in our galaxy. But which dwarf galaxy is doing the pulling, and whose gas is now being feasted upon? After years of debate, scientists now have the answer to this "whodunit" mystery.

"There's been a question: Did the gas come from the Large Magellanic Cloud or the Small Magellanic Cloud? At first glance, it looks like it tracks back to the Large Magellanic Cloud," explained lead researcher Andrew Fox of the Space Telescope Science Institute in Baltimore, Maryland. "But we've approached that question differently, by asking: What is the Leading Arm made of? Does it have the composition of the Large Magellanic Cloud or the composition of the Small Magellanic Cloud?"

Fox's research is a follow-up to his 2013 work, which focused on a trailing feature behind the Large and Small Magellanic Clouds. This gas in this ribbon-like structure, called the Magellanic Stream, was found to come from both dwarf galaxies. Now Fox wondered about its counterpart, the Leading Arm. Unlike the trailing Magellanic Stream, this tattered and shredded "arm" has already reached the Milky Way and survived its journey to the galactic disk.

The Leading Arm is a real-time example of gas accretion, the process of gas falling onto galaxies. This is very difficult to see in galaxies outside the Milky Way, because they are too far away and too faint. "As these two galaxies are in our backyard, we essentially have a front-row seat to view the action," said collaborator Kat Barger at Texas Christian University.

In a new kind of forensics, Fox and his team used Hubble's ultraviolet vision to chemically analyze the gas in the Leading Arm. They observed the light from seven quasars, the bright cores of active galaxies that reside billions of light-years beyond this gas cloud. Using Hubble's Cosmic Origins Spectrograph, the scientists measured how this light filters through the cloud.

In particular, they looked for the absorption of ultraviolet light by oxygen and sulfur in the cloud. These are good gauges of how many heavier elements reside in the gas. The team then compared Hubble's measurements to hydrogen measurements made by the National Science Foundation's Robert C. Byrd Green Bank Telescope at the Green Bank Observatory in West Virginia, as well as several other radio telescopes.

"With the combination of Hubble and Green Bank Telescope observations, we can measure the composition and velocity of the gas to determine which dwarf galaxy is the culprit," explained Barger.

After much analysis, the team finally had conclusive chemical "fingerprints" to match the origin of the Leading Arm's gas. "We've found that the gas matches the Small Magellanic Cloud," said Fox. "That indicates the Large Magellanic Cloud is winning the tug-of-war, because it has pulled so much gas out of its smaller neighbor."

This answer was possible only because of Hubble's unique ultraviolet capability. Because of the filtering effects of Earth's atmosphere, ultraviolet light cannot be studied from the ground. "Hubble is the only game in town," explained Fox. "All the lines of interest, including oxygen and sulfur, are in the ultraviolet. So if you work in the optical and infrared, you can't see them."

Gas from the Leading Arm is now crossing the disk of our galaxy. As it crosses, it interacts with the Milky Way's own gas, becoming shredded and fragmented.

This is an important case study of how gas gets into galaxies and fuels star birth. Astronomers use simulations and try to understand the inflow of gas in other galaxies. But here, the gas is being caught red-handed as it moves across the Milky Way's disk. Sometime in the future, planets and solar systems in our galaxy may be born out of material that used to be part of the Small Magellanic Cloud.

As Fox and his team look ahead, they hope to map out the full size of the Leading Arm-something that is still unknown.


Overview

Space and astronomy are subjects that have captivated people for ages. Without ever being able to experience their vastness, it can be challenging for us to comprehend what goes on in the market and how astronomy and planets operate.

But with a publication on the subject, we could become a bit more educated about the unknown and attempt to know ourselves on what is outside Earth. Whether you are a veteran space enthusiast or fancy learning a bit more about a specific component, there is a book available for you.


Research Box Title

Eerie, dramatic new pictures from NASA's Hubble Space Telescope show newborn stars emerging from "eggs" – not the barnyard variety – but rather dense, compact pockets of interstellar gas called evaporating gaseous globules (EGGs). Hubble found the "EGGs," appropriately enough, in the Eagle nebula, a nearby star-forming region 6,500 light- years away in the constellation Serpens.

"For a long time astronomers have speculated about what processes control the sizes of stars – about why stars are the sizes that they are," said Jeff Hester of Arizona State University, Tempe, AZ. "Now in M16 we seem to be watching at least one such process at work right in front of our eyes."

Striking pictures taken by Hester and co-investigators with Hubble's Wide Field and Planetary Camera 2 (WFPC2) resolve the EGGs at the tip of finger-like features protruding from monstrous columns of cold gas and dust in the Eagle nebula (also called M16 – 16th object in the Messier catalog). The columns – dubbed "elephant trunks" – protrude from the wall of a vast cloud of molecular hydrogen, like stalagmites rising above the floor of a cavern. Inside the gaseous towers, which are light-years long, the interstellar gas is dense enough to collapse under its own weight, forming young stars that continue to grow as they accumulate more and more mass from their surroundings.

Hubble gives a clear look at what happens as a torrent of ultraviolet light from nearby young, hot stars heats the gas along the surface of the pillars, "boiling it away" into interstellar space – a process called "photoevaporation. "The Hubble pictures show photoevaporating gas as ghostly streamers flowing away from the columns. But not all of the gas boils off at the same rate. The EGGs, which are denser than their surroundings, are left behind after the gas around them is gone.

"It's a bit like a wind storm in the desert," said Hester. "As the wind blows away the lighter sand, heavier rocks buried in the sand are uncovered. But in M16, instead of rocks, the ultraviolet light is uncovering the denser egg-like globules of gas that surround stars that were forming inside the gigantic gas columns."

Some EGGs appear as nothing but tiny bumps on the surface of the columns. Others have been uncovered more completely, and now resemble "fingers" of gas protruding from the larger cloud. (The fingers are gas that has been protected from photoevaporation by the shadows of the EGGs). Some EGGs have pinched off completely from the larger column from which they emerged, and now look like teardrops in space.

By stringing together these pictures of EGGs caught at different stages of being uncovered, Hester and his colleagues from the Wide Field and Planetary Camera Investigation Definition Team are getting an unprecedented look at what stars and their surroundings look like before they are truly stars.

"This is the first time that we have actually seen the process of forming stars being uncovered by photoevaporation," Hester emphasized. "In some ways it seems more like archaeology than astronomy. The ultraviolet light from nearby stars does the digging for us, and we study what is unearthed."

"In a few cases we can see the stars in the EGGs directly in the WFPC2 images," says Hester. "As soon as the star in an EGG is exposed, the object looks something like an ice cream cone, with a newly uncovered star playing the role of the cherry on top."

Ultimately, photoevaporation inhibits the further growth of the embyronic stars by dispersing the cloud of gas they were "feeding" from. "We believe that the stars in M16 were continuing to grow as more and more gas fell onto them, right up until the moment that they were cut off from that surrounding material by photoevaporation," said Hester.

This process is markedly different from the process that governs the sizes of stars forming in isolation. Some astronomers believe that, left to its own devices, a star will continue to grow until it nears the point where nuclear fusion begins in its interior. When this happens, the star begins to blow a strong "wind" that clears away the residual material. Hubble has imaged this process in detail in so-called Herbig-Haro objects.

Hester also speculated that photoevaporation might actually inhibit the formation of planets around such stars. It is not at all clear from the new data that the stars in M16 have reached the point where they have formed the disks that go on to become solar systems," said Hester, "and if these disks haven't formed yet, they never will."

Hester plans to use Hubble's high resolution to probe other nearby star-forming regions to look for similar structures. "Discoveries about the nature of the M16 EGGs might lead astronomers to rethink some of their ideas about the environments of stars forming in other regions, such as the Orion Nebula," he predicted.

BACKGROUND INFORMATION: M16 – STAR BIRTH IN THE NEST OF THE EAGLE

Stars are born from the gas of interstellar space. When they eventually burnout and die, they bequeath their legacy back to the interstellar medium from which they formed. The signposts marking this ongoing cycle of birth, death, and renewal would be easily visible to any casual observer who had a bird's-eye view of our pinwheel-shaped galaxy. Spread across our galaxy such an observer would see majestic spiral arms, highlighted by bright young stars and the glowing clouds of gas that those stars illuminate.

On a clear, dark summer night earth-based observers can see these glowing clouds, called nebulae, scattered along the track of the Milky Way. Many can be found by looking in the direction of the great star clouds in the summer constellation, Sagittarius.

One of the most unique star-birth regions is the Eagle Nebula, (also called M16 because it is in the Messier Catalog of "fuzzy" permanent objects in the sky, that was compiled more than 200 years ago by French astronomer Charles Messier) it is visible in binoculars near the border between the constellations of Sagittarius and Serpens. The nebula is actually a bowl-shaped blister on the side of a dense cloud of cold interstellar gas.

Most of this cloud is so dense and cool that its hydrogen atoms are bound as molecules. This "molecular hydrogen" is the raw material for building new stars. The cloud contains microscopic dust particles of carbon (in the form of graphite), silicates and other compounds similar to those found in terrestrial and lunar rocks. Though this trace dust accounts for only a fraction of the nebula's mass, it's enough dust to absorb visible light – cloaking some of the visual details of star birth.

A cluster of about 100 newborn stars glitters inside the open "bowl" of the nebula. A few of these stars are much more massive than our Sun is, and so are tremendously hotter and brighter than the Sun. The brightest of these stars may be 100,000 times brighter than the Sun and have temperatures of nearly 90,000 degrees Fahrenheit (50,000 degrees Kelvin).

These young stars emit intense ultraviolet radiation which is so energetic it heats the surrounding gas, causing it to glow like the gas inside a fluorescent light bulb. When this ultraviolet light hits the bowl-shaped surface of the molecular cloud, it heats that gas, causing it to "evaporate" and stream away from the surface. If one could watch the process for more than a million years, they would see the bowl grow increasingly larger as the radiation from the stars eats deeper into the molecular cloud.

Unlike other stellar nebula which we see face-on – like the great Orion Nebula – M16 presents astronomers with a unique side view of the structure of a typical star-birth region: the cluster of hot, young stars in the center of the cavity, the evaporating surface of the cloud, and finally the great cold mass of the cloud itself.

The Eagle Nebula's name comes from its symmetrical appearance which is reminiscent of a bird of prey with outstretched wings and talons bared. The Eagle's "talons" are actually a series of dense columns of gas that protrude into the interior of the nebula. These columns form as a result of the same process that causes the bowl to grow. Because the columns are denser than their surroundings, they are not evaporating as rapidly as the surrounding gas, and so remain. The process is analogous to the formation of towering buttes and spires in the deserts of the American Southwest. These geological features formed when wind and rain eroded away softer ground, but places where the rock was harder resisted erosion and were left behind.

Inside these interstellar columns, the gas density can get so high that gravity takes over and causes the gas to start collapsing into ever-smaller clumps. As more and more gas falls onto these growing clumps they get further compressed by their own weight, until finally they trigger nuclear fusion reactions in their cores, and "turn on" as stars.

However, in M16 this process may not get a chance to go on to completion. If a forming star and the gas cloud that surrounds it are "uncovered" by photoevaporation before the star finishes growing, the mass of the young star may be "frozen." The star can't grow any more simply because the cloud from which it was drawing material is gone. In M16 Hubble Space Telescope's high resolution seems to have caught about 50 stars in this situation.

These are called EGGs "evaporating gaseous globules." The acronym is appropriate because these EGGs are objects within which stars are being born and are now emerging.

M16 is where the action is today, but it won't remain so forever. Within another few million years, star formation will have exhausted or dispersed the available raw material, and the massive stars that illuminate the Eagle will have lived out their short lives and died in spectacular supernova explosions. But even though the "birth cloud" nebula will be gone, most of the stars that formed there will remain. The offspring of the Eagle will "take wing" among the rest of the hundreds of billions of stars that make up our galaxy.

Credits:NASA, ESA, STScI, J. Hester and P. Scowen (Arizona State University)


New Hubble mosaic of the Orion Nebula

In the search for rogue planets and failed stars astronomers using the NASA/ESA Hubble Space Telescope have created a new mosaic image of the Orion Nebula. During their survey of the famous star formation region, they found what may be the missing piece of a cosmic puzzle the third, long-lost member of a star system that had broken apart.

The Orion Nebula is the closest star formation region to Earth, only 1400 light-years away. It is a turbulent place -- stars are being born, planetary systems are forming and the radiation unleashed by young massive stars is carving cavities in the nebula and disrupting the growth of smaller, nearby stars.

Because of this ongoing turmoil, Hubble has observed the nebula many times to study the various intriguing processes going on there. This large composite image of the nebula's central region, combining visual and near-infrared data, is the latest addition to this collection.

Astronomers used these new infrared data to hunt for rogue planets -- free-floating in space without a parent star -- and brown dwarfs in the Orion Nebula. The infrared capabilities of Hubble also allow it to peer through the swirling clouds of dust and gas and make the stars hidden within clearly visible the unveiled stars appear with bright red colours in the final image. Among these, astronomers stumbled across a star moving at an unusually high speed -- about 200 000 kilometres per hour [1]. This star could be the missing piece of the puzzle of a star system that had been broken apart 540 years ago.

Astronomers already knew about two other runaway stars in the Orion Nebula which were most likely once part of a now-defunct multiple-star system. For years it was suspected that the original system contained more than just these two stars. Now, by virtue of accident and curiosity, Hubble may have found the missing third piece of this cosmic puzzle.

Whether the new star is indeed the missing -- and the last -- piece of the puzzle will require further observations. So will the answer to the question of why the original star system broke apart in the first place. While there are several theories -- interactions with other, nearby stellar groups, or two of the stars getting too close to each other -- none can be ruled out or confirmed yet.

And while the astronomers are looking for the answers to these questions, who knows what mystery they will find next?

[1] The relative speed of the star was calculated by comparing observations made in 1998 with the recent ones. The speed of the newly discovered star is almost 30 times the speed of most of the nebula's stellar inhabitants.


1) Looking down the edge of infinity: An image of M87's supermassive black hole

Nothing in astronomy captures people's attention and wonder like a black hole. Capable of utter destruction yet the engines of the formation of stars in galaxies as well, everything about them is fascinating and weird.

Yet for all the articles written about them, all the observations made of them, all the theoretical calculations made about them, we still have never actually seen one. And you can't. There's a reason we call them black holes.

But we can see their impact on the environment around them. Some are actively feeding, matter piling up in huge disks around them before falling over the cliff of infinity, and that material is extremely hot, glowing across the electromagnetic spectrum. The problem is that even though these disks can be light years across, they're so far away from Earth that distance shrinks them to irresolution.

… until now. Over the course of four nights in 2017, an array of seven telescopes across the planet were aimed at the heart of M87, a galaxy 55 million light years away in the constellation of Virgo. It's the nearest active galaxy, one with a supermassive black hole equal to 6.5 billion times the Sun's mass, and one that is accreting vast amounts of material. The observations were so difficult and complex it took nearly two years to process them, but when the results were released in April 2019, people across the planet gave out a collective gasp:

The very first image of the "shadow" of a supermassive black hole. This shows the region around a black hole with a mass 6.5 billion times that of the Sun, located 55 million light years away from Earth in the core of the galaxy M87. Credit: NSF

That picture is amazing. It's the actual image of material circling the black hole some few dozen billion kilometers out … and of course there's that gaping dark hole in the center. That's not the black hole itself! It's where material orbiting the black hole is so close that the light from it can actually orbit the hole a few times before falling in. That region is called the photon sphere, and is about 2.5 times bigger than the event horizon (the point of no return for anything getting too close to a black hole for M87 the event horizon is about 40 billion kilometers across, roughly eight times the distance of Neptune from the Sun). This area is sometimes called the shadow of the black hole, but I prefer to think of it as the silhouette. Either way, it's just an analogy. But it's where light cannot get out, so it looks like a donut hole.

Simulation of what a black hole with an accretion disk looks like, based on real physics. Credit: NASA’s Goddard Space Flight Center/Jeremy Schnittman

The image closely matches what we expected to see from a close-up image of a black hole. And it's only the first of its kind: The Event Horizon Telescope, as the array is collectively called, will be aimed at more soon, including Sgr A*, the supermassive black hole in our own galaxy. At just 26,000 light years away it's much closer, but far less massive and therefore smaller coincidentally the two black holes appear to be about the same apparent size our sky. I can't wait to see that one!

And with this new powerful technology, we'll be seeing a lot more from this array. We've known about black holes for a long time, but there's still a lot about them we don't understand. This image, and the ones that will no doubt follow, will help us wrap our heads around these objects that literally wrap space and time around them.


What's the best Astro view you've ever had

Several I could pick but I'll go with NGC 4565 through an 18" DOB at a GCSP. Looked like a photo!

Cloudy insomnia. just great!

#2 kfiscus

Naked-eye prominences at 1991's total solar eclipse and then the diamond ring at third contact. Hairs standing up on the back of my neck.

#3 clusterbuster

A view of OMEGA CENTAURUS through my friends C14 from South Florida (Kissimee Prairie Park), on a night with the BEST SEEING that I had ever seen. It was Breathtaking ! For Sure !

#4 Allan Wade

NGC 3242, Ghost of Jupiter in a 32" with 7mm Delite at 480x. One of my favourites in my 12", but in a 32" it looked like a completely different object. That dob was so good in fact that just about every planetary we looked at was better visually than any images I've seen of them.

EDIT: Hubble images not included

Edited by Allan Wade, 29 June 2016 - 04:57 AM.

#5 Laika

#6 tchandler

47 Tuc through a 12" SCT was pretty nice. But the view that knocked my socks clean off (and they're still A.W.O.L.) was a view with 12 year old eyes of Saturn through a wiggly 60 mm refractor when I was not expecting to see Saturn.

#7 Chucky

M51 thru Carl Wright's 22 Starstructure at Chiefland, Florida --- thru his video screen (Mallincam). Totally blew me away!

Edited by Chucky, 29 June 2016 - 07:23 AM.

#8 Jon Isaacs

That's a tough question, I don't really rate the views. Most memorable, there are many memorable, splitting zeta Bootis at around 0.4 arc-seconds with my refigured 16 inch, M42 in my 25 inch, NGC1999 in the big scope..

But the most memorable view, the most important view:

About 30 years ago, I had invested $5 in a garage sale 60 mm refractor. It was worn out, dirty, only one Huygenian eyepiece, no finder. I cleaned the best I could, it was what I could afford with a new job and feeding three growing boys. I had read one sentence in the Peterson guide that included 60 mm refractors as a worthwhile scope. That was enough for me.

We were camped at the Painted Rock campground outside of Gila Bend and early one cold morning, I woke up and got out of my sleeping bag, and took the scope out to look around. I just wanted to look. With no finder and no chart, I was just wandering around taking in what serendipity offered me. There was about 15 minutes there where I thought that a reflected ghost from Venus was a new comet, I eventually got that one figured out.

But then serendipity smiled on me, I stumbled across a tiny, faint bit of nebulosity surrounding a star and that was it, I just couldn't get enough of it. In just had to see more, I still have to see more, that moment has never ended. As one would expect, I later identified it as the great nebula in Orion.

But that moment, it changed my life. Eventually that scope was stolen from a second story balcony. Now days I have much better equipment, I know a whole lot more, i am much more skilled at seeing faint objects, but I am still doing the same thing, just going out there to look around, hoping serendipity will smile on me one more time.


Space Junk “Meteor” Re-Entry Over UK

A sporadic meteor fireball, believed to be a large piece of space junk, entered Earth’s atmosphere over the UK last night sparking wide-spread reaction across the country. Many emergency calls were made by members of the public and a media frenzy ensued. At the moment it is believed that the fireball was an old satellite or fragment of spacecraft which slowly deorbited over time until burning up in the upper atmosphere due to air resistance at 18,000 miles per hour.
Meteor fireballs are not necessarily an uncommon sight, and are generally seen during meteor showers when larger fragments of rock and dust enter the atmosphere. The difference between a meteor and a fireball is simply size, with fireballs being brighter and sometimes breaking up into smaller fragments during their descent.
Satellites generally experience a small amount of drag from both tenuous gas in the highest reaches of the atmosphere and from minor collisions with space debris. Unless a spacecraft uses small thrusters to regain altitude, as happens with the International Space Station, it will eventually enter the atmosphere, burning up on its way. It is very rare for an object to make it all the way down to impact at ground level as the air resistance breaks most things down into small fragments early on in their descent- the same reason for meteors and fireballs appearing so high in the atmosphere.
No impact from last nights meteor has been reported, but a huge number of people have reported their sightings of this spectacular phenomenon across the country. The night sky may appear constant and unchanging, but this brings the real power of the universe home.


Space Junk “Meteor” Re-Entry Over UK

A sporadic meteor fireball, believed to be a large piece of space junk, entered Earth’s atmosphere over the UK last night sparking wide-spread reaction across the country. Many emergency calls were made by members of the public and a media frenzy ensued. At the moment it is believed that the fireball was an old satellite or fragment of spacecraft which slowly deorbited over time until burning up in the upper atmosphere due to air resistance at 18,000 miles per hour.
Meteor fireballs are not necessarily an uncommon sight, and are generally seen during meteor showers when larger fragments of rock and dust enter the atmosphere. The difference between a meteor and a fireball is simply size, with fireballs being brighter and sometimes breaking up into smaller fragments during their descent.
Satellites generally experience a small amount of drag from both tenuous gas in the highest reaches of the atmosphere and from minor collisions with space debris. Unless a spacecraft uses small thrusters to regain altitude, as happens with the International Space Station, it will eventually enter the atmosphere, burning up on its way. It is very rare for an object to make it all the way down to impact at ground level as the air resistance breaks most things down into small fragments early on in their descent- the same reason for meteors and fireballs appearing so high in the atmosphere.
No impact from last nights meteor has been reported, but a huge number of people have reported their sightings of this spectacular phenomenon across the country. The night sky may appear constant and unchanging, but this brings the real power of the universe home.