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Forum:Satellites - Robotic Probes
Topic:Hubble Space Telescope: New observations
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PhilipExcellent and amazing new images of the center of our galaxy... IYA2009 worthy.
PhilipNASA release
Suspected Asteroid Collision Leaves Trailing Debris

NASA's Hubble Space Telescope has observed a mysterious X-shaped debris pattern and trailing streamers of dust that suggest a head-on collision between two asteroids. Astronomers have long thought the asteroid belt is being ground down through collisions, but such a smashup has never been seen before.


Credit: NASA, ESA, and D. Jewitt

Asteroid collisions are energetic, with an average impact speed of more than 11,000 miles per hour, or five times faster than a rifle bullet. The comet-like object imaged by Hubble, called P/2010 A2, was first discovered by the Lincoln Near-Earth Asteroid Research, or LINEAR, program sky survey on Jan. 6. New Hubble images taken on Jan. 25 and 29 show a complex X-pattern of filamentary structures near the nucleus.

"This is quite different from the smooth dust envelopes of normal comets," said principal investigator David Jewitt of the University of California at Los Angeles. "The filaments are made of dust and gravel, presumably recently thrown out of the nucleus. Some are swept back by radiation pressure from sunlight to create straight dust streaks. Embedded in the filaments are co-moving blobs of dust that likely originated from tiny unseen parent bodies."

Hubble shows the main nucleus of P/2010 A2 lies outside its own halo of dust. This has never been seen before in a comet-like object. The nucleus is estimated to be 460 feet in diameter.

Normal comets fall into the inner regions of the solar system from icy reservoirs in the Kuiper belt and Oort cloud. As comets near the sun and warm up, ice near the surface vaporizes and ejects material from the solid comet nucleus via jets. But P/2010 A2 may have a different origin. It orbits in the warm, inner regions of the asteroid belt where its nearest neighbors are dry rocky bodies lacking volatile materials.

This leaves open the possibility that the complex debris tail is the result of an impact between two bodies, rather than ice simply melting from a parent body.

"If this interpretation is correct, two small and previously unknown asteroids recently collided, creating a shower of debris that is being swept back into a tail from the collision site by the pressure of sunlight," Jewitt said.

The main nucleus of P/2010 A2 would be the surviving remnant of this so-called hypervelocity collision.

"The filamentary appearance of P/2010 A2 is different from anything seen in Hubble images of normal comets, consistent with the action of a different process," Jewitt said. An impact origin also would be consistent with the absence of gas in spectra recorded using ground-based telescopes.

The asteroid belt contains abundant evidence of ancient collisions that have shattered precursor bodies into fragments. The orbit of P/2010 A2 is consistent with membership in the Flora asteroid family, produced by collisional shattering more than 100 million years ago. One fragment of that ancient smashup may have struck Earth 65 million years ago, triggering a mass extinction that wiped out the dinosaurs. But, until now, no such asteroid-asteroid collision has been caught "in the act."

At the time of the Hubble observations, the object was approximately 180 million miles from the sun and 90 million miles from Earth. The Hubble images were recorded with the new Wide Field Camera 3 (WFC3), which is capable of detecting house-sized fragments at the distance of the asteroid belt.

Robert PearlmanNASA release
Pluto's White, Dark-Orange and Charcoal-Black Terrain Captured by NASA's Hubble

NASA has released the most detailed and dramatic images ever taken of the distant dwarf planet Pluto. The images from NASA's Hubble Space Telescope show an icy, mottled, dark molasses-colored world undergoing seasonal surface color and brightness changes.

Pluto has become significantly redder, while its illuminated northern hemisphere is getting brighter. These changes are most likely consequences of surface ice melting on the sunlit pole and then refreezing on the other pole, as the dwarf planet heads into the next phase of its 248-year-long seasonal cycle. Analysis shows the dramatic change in color took place from 2000 to 2002.


Credit: NASA, ESA, and M. Buie/Southwest Research Institute

The Hubble pictures confirm Pluto is a dynamic world that undergoes dramatic atmospheric changes not simply a ball of ice and rock. These dynamic seasonal changes are as much propelled by the planet's 248-year elliptical orbit as by its axial tilt. Pluto is unlike Earth, where the planet's tilt alone drives seasons. Pluto's seasons are asymmetric because of its elliptical orbit. Spring transitions to polar summer quickly in the northern hemisphere, because Pluto is moving faster along its orbit when it is closer to the sun.

Ground-based observations, taken in 1988 and 2002 show the mass of the atmosphere doubled during that time. This may be because of warming and melting nitrogen ice. The new Hubble images are giving astronomers essential clues about the seasons on Pluto and the fate of its atmosphere.

When the Hubble pictures taken in 1994 are compared to those of 2002 and 2003, astronomers see evidence that the northern polar region has gotten brighter, while the southern hemisphere darkened. These changes hint at very complex processes affecting the visible surface.

The images will help planetary astronomers interpret more than three decades of Pluto observations from other telescopes.
"The Hubble observations are the key to tying together these other diverse constraints on Pluto and showing how it all makes sense by providing a context based on weather and seasonal changes, which opens other new lines of investigation," says principal investigator Marc Buie of the Southwest Research Institute in Boulder, Colo.

These Hubble images, taken by the Advanced Camera for Surveys, will remain the sharpest view of Pluto until NASA's New Horizons probe is within six months of its flyby during 2015. The Hubble images are invaluable for picking the planet's most interesting hemisphere for imaging by the New Horizons probe.

New Horizons will pass by Pluto so quickly that only one hemisphere will be photographed in detail. Particularly noticeable in the Hubble images is a bright spot that has been independently noted to be unusually rich in carbon monoxide frost. It is a prime target for New Horizons. "Everybody is puzzled by this feature," Buie said. New Horizons will get an excellent look at the boundary between this bright feature and a nearby region covered in pitch-black surface material.

"The Hubble images also will help New Horizons scientists better calculate the exposure time for each Pluto snapshot which is important for taking the most detailed pictures possible," Buie said. With no chance for re-exposures, accurate models for the surface of Pluto are essential for properly exposed images.

The Hubble images surface variations a few hundred miles across that are too coarse for understanding surface geology. But in terms of surface color and brightness, Hubble reveals a complex-looking world with white, dark-orange and charcoal-black terrain. The overall color is believed to be a result of ultraviolet radiation from the distant sun breaking up methane present on Pluto's surface, leaving behind a dark and red-carbon-rich residue.

The Hubble images are a few pixels wide. Through a technique called dithering, multiple, slightly offset pictures are combined through computer-image processing to synthesize a higher-resolution view than can be seen in a single exposure.

"This has taken four years and 20 computers operating continuously and simultaneously to accomplish," Buie said. Buie developed the special algorithms to sharpen the Hubble data. He plans to use Hubble's new Wide Field Camera 3 to make additional observations prior to the arrival of New Horizons.

Robert PearlmanNASA release
NASA's Hubble Finds Most Distant Galaxy Candidate Ever Seen in Universe

Astronomers have pushed NASA's Hubble Space Telescope to its limits by finding what is likely to be the most distant object ever seen in the universe. The object's light traveled 13.2 billion years to reach Hubble, roughly 150 million years longer than the previous record holder. The age of the universe is approximately 13.7 billion years.

The tiny, dim object is a compact galaxy of blue stars that existed 480 million years after the big bang. More than 100 such mini-galaxies would be needed to make up our Milky Way. The new research offers surprising evidence that the rate of star birth in the early universe grew dramatically, increasing by about a factor of 10 from 480 million years to 650 million years after the big bang.

"NASA continues to reach for new heights, and this latest Hubble discovery will deepen our understanding of the universe and benefit generations to come,” said NASA Administrator Charles Bolden, who was the pilot of the space shuttle mission that carried Hubble to orbit. “We could only dream when we launched Hubble more than 20 years ago that it would have the ability to make these types of groundbreaking discoveries and rewrite textbooks.”

Astronomers don't know exactly when the first stars appeared in the universe, but every step farther from Earth takes them deeper into the early formative years when stars and galaxies began to emerge in the aftermath of the big bang.

"These observations provide us with our best insights yet into the earlier primeval objects that have yet to be found," said Rychard Bouwens of the University of Leiden in the Netherlands. Bouwens and Illingworth report the discovery in the Jan. 27 issue of the British science journal Nature.

This observation was made with the Wide Field Camera 3 starting just a few months after it was installed in the observatory in May 2009, during the last NASA space shuttle servicing mission to Hubble. After more than a year of detailed observations and analysis, the object was positively identified in the camera's Hubble Ultra Deep Field-Infrared data taken in the late summers of 2009 and 2010.

The object appears as a faint dot of starlight in the Hubble exposures. It is too young and too small to have the familiar spiral shape that is characteristic of galaxies in the local universe. Although its individual stars can't be resolved by Hubble, the evidence suggests this is a compact galaxy of hot stars formed more than 100-to-200 million years earlier from gas trapped in a pocket of dark matter.

"We're peering into an era where big changes are afoot," said Garth Illingworth of the University of California at Santa Cruz. "The rapid rate at which the star birth is changing tells us if we go a little further back in time we're going to see even more dramatic changes, closer to when the first galaxies were just starting to form."

The proto-galaxy is only visible at the farthest infrared wavelengths observable by Hubble. Observations of earlier times, when the first stars and galaxies were forming, will require Hubble’s successor, the James Webb Space Telescope (JWST).

The hypothesized hierarchical growth of galaxies -- from stellar clumps to majestic spirals and ellipticals -- didn't become evident until the Hubble deep field exposures. The first 500 million years of the universe's existence, from a z of 1000 to 10, is the missing chapter in the hierarchical growth of galaxies. It's not clear how the universe assembled structure out of a darkening, cooling fireball of the big bang. As with a developing embryo, astronomers know there must have been an early period of rapid changes that would set the initial conditions to make the universe of galaxies what it is today.

"After 20 years of opening our eyes to the universe around us, Hubble continues to awe and surprise astronomers," said Jon Morse, NASA's Astrophysics Division director at the agency's headquarters in Washington. "It now offers a tantalizing look at the very edge of the known universe -- a frontier NASA strives to explore."

Hubble is a project of international cooperation between NASA and the European Space Agency. NASA's Goddard Space Flight Center in Greenbelt, Md., manages the telescope. The Space Telescope Science Institute (STScI) conducts Hubble science operations. STScI is operated for NASA by the Association of Universities for Research in Astronomy, Inc., in Washington.

DChudwin2011 marks Neptune's first complete revolution around the Sun since it was discovered in 1846. To commemorate the occasion, NASA’s Hubble Space Telescope took images of Neptune showing its cloud cover on June 25-26. NASA has just released the pictures.
Neptune Completes Its First Circuit Around The Sun Since Its Discovery

These four images of Neptune were taken by NASA's Hubble Space Telescope during the planet's 16-hour rotation. The snapshots were taken at roughly four-hour intervals, offering a full view of the blue-green planet.

Today (July 12, 2011) marks Neptune's first orbit around the Sun since it was discovered nearly 165 years ago. These images were taken to commemorate the event.

The Hubble images, taken with the Wide Field Camera 3 on June 25-26, reveal high-altitude clouds in the northern and southern hemispheres. The clouds are composed of methane ice crystals.

In the Hubble images, absorption of red light by methane in Neptune's atmosphere gives the planet its distinctive aqua color. The clouds look pink because they are reflecting near-infrared light.

A faint, dark band near the bottom of the southern hemisphere is probably caused by a decrease in the hazes in the atmosphere that scatter blue light. The band was imaged by NASA's Voyager 2 spacecraft in 1989, and may be tied to circumpolar circulation created by high-velocity winds in that region. Neptune is the most distant major planet in our solar system.

German astronomer Johann Galle discovered the planet on September 23, 1846. At the time, the discovery doubled the size of the known solar system. The planet is 2.8 billion miles (4.5 billion kilometers) from the Sun, 30 times farther than Earth.

Under the Sun's weak pull at that distance, Neptune plods along in its huge orbit, slowly completing one revolution approximately every 165 years.

Sean Walker of Sky & Telescope prepared a video showing the rotation of Neptune.

While Voyager flew past Neptune in 1989, there are no current plans for any return in our lifetimes. The New Horizons spacecraft, on the way to Pluto, passes past Neptune's orbit but is nowhere near the blue planet.

PhilipSuperb image of the Necklace nebula. STScI release
Hubble Offers a Dazzling View of the 'Necklace' Nebula

A giant cosmic necklace glows brightly in this NASA Hubble Space Telescope image.

The object, aptly named the Necklace Nebula, is a recently discovered planetary nebula, the glowing remains of an ordinary, Sun-like star. The nebula consists of a bright ring, measuring 12 trillion miles across, dotted with dense, bright knots of gas that resemble diamonds in a necklace. The knots glow brightly due to absorption of ultraviolet light from the central stars.

A pair of stars orbiting very close together produced the nebula, also called PN G054.2-03.4. About 10,000 years ago one of the aging stars ballooned to the point where it enveloped its companion star. This caused the larger star to spin so fast that much of its gaseous envelope expanded into space. Due to centrifugal force, most of the gas escaped along the star's equator, producing a dense ring. The embedded bright knots are the densest gas clumps in the ring.

The stars are furiously whirling around each other, completing an orbit in a little more than a day. (For comparison, Mercury, the closest planet to the Sun, takes 88 days to orbit the Sun.)

The Necklace Nebula is located 15,000 light-years away in the constellation Sagitta (the Arrow). In this composite image, taken on July 2, 2011, Hubble's Wide Field Camera 3 captured the glow of hydrogen (blue), oxygen (green), and nitrogen (red).

DChudwinHere is a compilation of some of the best images from the Hubble Telescope as chosen by The Baltimore Sun.
In the 23 years since the Hubble Space Telescope was launched, the satellite observatory has transmitted countless photographs to NASA astronomers. In recent months, the telescope has captured galaxies colliding, comets soaring through space and bright nebulas expanding.
Robert PearlmanNASA/STScI/ESA release
Hubble spots azure blue planet

Astronomers using the NASA/ESA Hubble Space Telescope have, for the first time, determined the true colour of a planet orbiting another star. If seen up close this planet, known as HD 189733b, would be a deep azure blue, reminiscent of Earth's colour as seen from space.

But that's where the similarities end. This "deep blue dot" is a huge gas giant orbiting very close to its host star. The planet's atmosphere is scorching with a temperature of over 1000 degrees Celsius, and it rains glass, sideways, in howling 7000 kilometre-per-hour winds. [1]

At a distance of 63 light-years from us, this turbulent alien world is one of the nearest exoplanets to Earth that can be seen crossing the face of its star. It has been intensively studied by Hubble and other telescopes, and its atmosphere has been found to be dramatically changeable and exotic, with hazes and violent flares. Now, this planet is the subject of an important first: the first measurement of an exoplanet's visible colour.

"This planet has been studied well in the past, both by ourselves and other teams," says Frédéric Pont of the University of Exeter, UK, leader of the Hubble observing programme and an author of this new paper. "But measuring its colour is a real first — we can actually imagine what this planet would look like if we were able to look at it directly."

In order to measure what this planet would look like to our eyes, the astronomers measured how much light was reflected off the surface of HD 189733b — a property known as albedo. [2]

HD 189733b is faint and close to its star. To isolate the planet's light from this starlight, the team used Hubble's Space Telescope Imaging Spectrograph (STIS) to peer at the system before, during, and after the planet passed behind its host star as it orbited. As it slipped behind its star, the light reflected from the planet was temporarily blocked from view, and the amount of light observed from the system dropped. But this technique also shows how the light changes in other ways — for example, its colour. [3]

"We saw the brightness of the whole system drop in the blue part of the spectrum when the planet passed behind its star," explains Tom Evans of the University of Oxford, UK, first author of the paper. "From this, we can gather that the planet is blue, because the signal remained constant at the other colours we measured."

The planet's azure blue colour does not come from the reflection of a tropical ocean, but is due to a hazy, turbulent atmosphere thought to be laced with silicate particles, which scatter blue light. [4] Earlier observations using different methods have reported evidence for scattering of blue light on the planet, but these most recent Hubble observations give robust confirming evidence, say the researchers.

HD 189733b presented a favourable case for these kinds of measurements as it belongs to a class of planets known as "hot Jupiters". These massive planets are similar in size to the gas giants in the Solar System, but instead lie very close to their parent star — this size and proximity to their star make them perfect subjects for exoplanet hunting. We know that hot Jupiters are numerous throughout the Universe. As we do not have one close to home in our own Solar System, studies of planets like HD 189733b are important to help us understand these dramatic objects.

"It's difficult to know exactly what causes the colour of a planet's atmosphere, even for planets in the Solar System," says Pont [5]. "But these new observations add another piece to the puzzle over the nature and atmosphere of HD 189733b. We are slowly painting a more complete picture of this exotic planet."

Notes

  1. In 2007 NASA's Spitzer Space Telescope measured the infrared light from the planet, producing one of the first ever temperature maps for an exoplanet. The map shows that day- and night-side temperatures differ by about 260 degrees Celsius, causing fierce winds to roar across the planet. The condensation temperature of the silicates (over 1300 degrees Celsius) mean these particles could form very small grains of glass in the atmosphere.

  2. Albedo is a measure of how much incident radiation is reflected. The greater the albedo, the greater the amount of light reflected. This value ranges from 0 to 1, with 1 being perfect reflectivity and 0 being a completely black surface. The Earth has an albedo of around 0.4.

  3. This technique is possible because the planet's orbit is tilted edge-on as viewed from Earth, so that it routinely passes in front of and behind the star. When the planet passes behind its host star, the light received from the system drops by about one part in 10 000.

  4. The deep blue colour of HD 189733b is consistent with the "red sunset of HD 189733b" result from the transit spectrum (heic0720). If sodium absorbs red light and dust scatters red light, the atmosphere will redden light shining through it, but will appear blue in reflected light.

  5. The colours of Jupiter and Venus are both due to unknown particles within the atmospheres of the planets. Earth looks blue from space because the oceans absorb red and green wavelengths more strongly than blue ones, and reflect the blueish hue of our sky. The shorter blue wavelengths of sunlight are selectively scattered by oxygen and nitrogen molecules in our atmosphere via a process called Rayleigh scattering.

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