Friday, December 23, 2011

Shell Galaxy NGC 7600

Friday, December 23, 2011
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Similar in size to the Milky Way, elliptical galaxy NGC 7600 is about 150 thousand light-years distant. In this deep image, spanning about 1/2 degree on the sky toward the constellation Aquarius, NGC 7600 sports a remarkable outer halo of nested shells and broad circumgalactic structures. The tantalizing features can be explained by the accretion of dark matter and stars on a cosmic timescale. In fact, a movie generated by simulating galaxy formation using a cosmological model with cold dark matter for the halos of merging galaxies reproduces the appearance of NGC 7600 in amazing detail. The remarkable simulation movie is available here on Vimeo and here in other formats. It presents compelling evidence that detailed features of galaxy mergers observed with small, wide field telescopes on planet Earth, are natural consequences of galaxy formation and fundamental properties of dark matter.

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Thursday, December 22, 2011

Through a Sun Tunnel

Thursday, December 22, 2011
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Today the Sun stands still at 05:30 UT. Halting its steady march toward southern declinations and begining its annual journey north, the event is known as a solstice. In the northern hemisphere December's solstice marks the astronomical start of winter. And if you're in the Great Basin Desert outside of Lucin, Utah, USA, near solstice dates you can watch the Sun rise and set through Sun Tunnels. A monumental earthwork by artist Nancy Holt, the Sun Tunnels are constructed of four 9 foot diameter cast concrete pipes each 18 feet long. The tunnels are arranged in a wide X to achieve the solstitial sunset and sunrise alignments. In this dramatic snapshot through a Sun Tunnel the Sun is just on the horizon. The cold, cloudy sunset was near the 2010 winter solstice. During daylight hours, holes in the sides of the pipes project spots of sunlight on their interior walls, forming a map of the principal stars in the constellations Draco, Perseus, Columba, and Capricorn. Fans of planet earthworks and celestial landart should note that the Sun Tunnels are about 150 miles by car from Robert Smithson's (Holt's late husband) Spiral Jetty.

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Wednesday, December 21, 2011

A Horseshoe Einstein Ring from Hubble

Wednesday, December 21, 2011
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What's large and blue and can wrap itself around an entire galaxy? A gravitational lens mirage. Pictured above, the gravity of a luminous red galaxy (LRG) has gravitationally distorted the light from a much more distant blue galaxy. More typically, such light bending results in two discernible images of the distant galaxy, but here the lens alignment is so precise that the background galaxy is distorted into a horseshoe -- a nearly complete ring. Since such a lensing effect was generally predicted in some detail by Albert Einstein over 70 years ago, rings like this are now known as Einstein Rings. Although LRG 3-757 was discovered in 2007 in data from the Sloan Digital Sky Survey (SDSS), the image shown above is a follow-up observation taken with the Hubble Space Telescope's Wide Field Camera 3. Strong gravitational lenses like LRG 3-757 are more than oddities -- their multiple properties allow astronomers to determine the mass and dark matter content of the foreground galaxy lenses.

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Tuesday, December 20, 2011

NGC 253: The Sculptor Galaxy

Tuesday, December 20, 2011
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NGC 253 is not only one of the brightest spiral galaxies visible, it is also one of the dustiest. Discovered in 1783 by Caroline Herschel in the constellation of Sculptor, NGC 253 lies only about ten million light-years distant. NGC 253 is the largest member of the Sculptor Group of Galaxies, the nearest group to our own Local Group of Galaxies. The dense dark dust accompanies a high star formation rate, giving NGC 253 the designation of starburst galaxy. Visible in the above photograph is the active central nucleus, also known to be a bright source of X-rays and gamma rays.

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Monday, December 19, 2011

A Geminid Meteor Over Iran

Monday, December 19, 2011
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Some beautiful things begin as grains of sand. Locked in an oyster, a granule grows into an iridescent pearl, lustrous and lovely to behold. While hurtling through the atmosphere at 35 kilometers per second, a generous cosmic sand grain becomes an awe-inspiring meteor, its transient beauty displayed for any who care to watch. This years Geminid meteor shower peaked last week with sky enthusiasts counting as many as 150 meteors per hour, despite the din of bright moon. Pictured above the Taftan volcano in southeast Iran, a meteor streaks between the bright star Sirius on the far left and the familiar constellation of Orion toward the image center. Sky watchers are looking forward to next years Geminids which should peak during a unobstructive new Moon.

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Sunday, December 18, 2011

Hints of Higgs from the Large Hadron Collider

Sunday, December 18, 2011
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Why do objects have mass? To help find out, Europe's CERN has built the Large Hadron Collider (LHC), the most powerful particle accelerator yet created by humans. Since 2008, the LHC has smashed protons into each other with unprecedented impact speeds. The LHC is exploring the leading explanation that mass arises from ordinary particles slogging through an otherwise invisible but pervasive field of virtual Higgs particles. Were high energy colliding particles to create real Higgs bosons, the Higgs mechanism for mass creation would be bolstered. Last week, two LHC groups reported on preliminary indications that the Higgs boson might exist around 120 GeV in mass. Data from the LHC collisions are also being scanned for micro black holes, magnetic monopoles, and exploring the possibility that every type of fundamental particle we know about has a nearly invisible supersymmetric counterpart. You can help -- the LHC@Home project will allow anyone with a home computer to help LHC scientists search archived LHC data for these strange beasts. Pictured above, a person stands in front of the huge ATLAS detector, one of six detectors attached to the LHC.

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Saturday, December 17, 2011

Comet Lovejoy: Sungrazing Survivor

Saturday, December 17, 2011
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Like most other sungrazing comets, Comet Lovejoy (C/2011 W3) was not expected to survive its close encounter with the Sun. But it did. This image from a coronograph onboard the sun-staring SOHO spacecraft identifies the still inbound remnants of the tail, with the brilliant head or coma emerging from the solar glare on December 16. The Sun's position, behind an occulting disk to block the overwhelming glare, is indicated by the white circle. Separated from its tail, Comet Lovejoy's coma is so bright it saturates the camera's pixels creating the horizontal streaks. Based on their orbits, sungrazer comets are thought to belong to the Kreutz family of comets, created by successive break ups from a single large parent comet that passed very near the Sun in the twelfth century. Most have been discovered with SOHO's cameras, but unlike many sungrazers, this one was first spotted by Australian astronomer Terry Lovejoy from an earth-based observatory. Comet Lovejoy is estimated to have come within 120,000 kilometers of the Sun's surface and likely had a large cometary nucleus to have survived its intense perihelion passage. Remarkable videos of the encounter from the Solar Dynamics Observatory can be found here.

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Friday, December 16, 2011

Red Moon Rising

Friday, December 16, 2011
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This surreal, wintry scene is a composite picture recorded on December 10 as the Moonrose behind the Zagros Mountains of Iran. A total lunar eclipse was already in progress. The image combines nearly 500 successive frames taken over 1.5 hours beginning in twilight as the eclipsed Moon steadily climbed above the rugged landscape. The reddened lunar disk and deep blue twilight make for a striking contrast, yet the contrasting colors have the same root cause. The eclipsed Moon is red because the Earth's umbral shadow is suffused with a faint red light. The ruddy illumination is from all the reddened sunsets and sunrises, as seen from a lunar perspective. But the sunsets and sunrises are reddened because the Earth's atmosphere scatters blue light more strongly than red, creating the twilight sky's dim, blue glow.

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Thursday, December 15, 2011

The Umbra of Earth

Thursday, December 15, 2011
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The dark, inner shadow of planet Earth is called the umbra. Shaped like a cone extending into space, it has a circular cross section most easily seen during a lunar eclipse. For example, last Saturday the Full Moon slid across the southern half of Earth's umbral shadow, entertaining moonwatchers around much of the planet. In the total phase of the eclipse, the Moon was completely within the umbra for 51 minutes. Recorded from Beijing, China, this composite eclipse image uses successive pictures from totality (center) and partial phases to trace out a large part of the umbra's curved edge. Background stars are visible in the darker eclipse phases. The result shows the relative size of the shadow's cross section at the distance of the Moon, as well as the Moon's path through Earth's umbra.

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Wednesday, December 14, 2011

A Lunar Eclipse Over an Indian Peace Pagoda

Wednesday, December 14, 2011
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Our Moon turned red last week. The reason was that during December 10, a total lunar eclipse occurred. The above digitally superimposed image mosaic captured the Moon many times during the eclipse, from before the Moon entered Earth's shadow until after the Moon exited. The image sequence was recorded over a Shanti Stupa Peace Pagota near the center of New Delhi, India, where the eclipse of the Moon was nearly, but not completely, total. The red tint of the eclipsed Moon was created by sunlight first passing through the Earth's atmosphere, which preferentially scatters blue light (making the sky blue) but passes and refracts red light, before reflecting back off the Moon. Differing amounts of clouds and volcanic dust in the Earth's atmosphere make each lunar eclipse appear differently. The next total lunar eclipse will occur only in 2014.

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Tuesday, December 13, 2011

In the Vicinity of the Cone Nebula

Tuesday, December 13, 2011
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Strange shapes and textures can be found in neighborhood of the Cone Nebula. The unusual shapes originate from fine interstellar dust reacting in complex ways with the energetic light and hot gas being expelled by the young stars. The brightest star on the right of the above picture is S Mon, while the region just below it has been nicknamed the Fox Fur Nebula for its color and structure. The blue glow directly surrounding S Mon results from reflection, where neighboring dust reflects light from the bright star. The red glow that encompasses the whole region results not only from dust reflection but also emission from hydrogen gas ionized by starlight. S Mon is part of a young open cluster of stars named NGC 2264, located about 2500 light years away toward the constellation of the Unicorn (Monoceros). The origin of the mysterious geometric Cone Nebula, visible on the far left, remains a mystery.

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Monday, December 12, 2011

An Unusual Vein of Deposited Rock on Mars

Monday, December 12, 2011
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What could create this unusual vein of rock on Mars? A leading hypothesis is that this thin rock layer dubbed "Homestake" was deposited by a running liquid -- like most mineral veins are here on Earth. And the running liquid of choice is water. Therefore, this mineral streak -- rich in calcium and sulfur -- is the latest in the growing body of evidence that part of Mars had a watery past. This, in turn, increases the speculation that Mars was once hospitable to life. Pictured above is a vista taken near the western rim of Endeavour Crater by the Opportunity rover currently exploring Mars. The inset image shows a close up of the recently discovered mineral vein.

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Sunday, December 11, 2011

Searching for Meteorites in Antarctica

Sunday, December 11, 2011
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Where is the best place on Earth to find meteorites? Although meteors fall all over the world, they usually just sink to the bottom of an ocean, are buried by shifting terrain, or are easily confused with terrestrial rocks. At the bottom of the Earth, however, in East Antarctica, huge sheets of blue ice remain pure and barren. When traversing such a sheet, a dark rock will stick out. These rocks have a high probability of being true meteorites -- likely pieces of another world. An explosion or impact might have catapulted these meteorites from the Moon, Mars, or even an asteroid, yielding valuable information about these distant worlds and our early Solar System. Small teams of snowmobiling explorers so far have found thousands. Pictured above, ice-trekkers search a field 25-kilometers in front of Otway Massif in the Transantarctic Mountain Range during the Antarctic summer of 1995-1996. The week marks the 100th anniversary of humans first reaching the Earth's South Pole.

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Saturday, December 10, 2011

Vesta Rocks

Saturday, December 10, 2011
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These colorful images are of thin slices of meteorites viewed through a polarizing microscope. Part of the group classified as HED meteorites for their mineral content (Howardite, Eucrite, Diogenite), they likely fell to Earth from 4 Vesta, the mainbelt asteroid currently being explored by NASA's Dawn spacecraft. Why are they thought to be from Vesta? Because the HED meteorites have visible and infrared spectra that match the spectrum of that small world. The hypothesis of their origin on Vesta is also consistent with data from Dawn's ongoing observations. Excavated by impacts, the diogenites shown here would have originated deep within the crust of Vesta. Similar rocks are also found in the lower crust of planet Earth. A sample scale is indicated by the white bars, each 2 millimeters long.

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Friday, December 9, 2011

Total Lunar Eclipse of December 10

Friday, December 9, 2011
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The last eclipse of 2011 is a total lunar eclipse that takes place at the Moon's descending node in eastern Taurus, four days after apogee. 

The Moon's orbital trajectory takes it through the southern half of Earth's umbral shadow. Although the eclipse is not central, the total phase still lasts 51 minutes. The Moon's path through Earth's shadows as well as a map illustrating worldwide visibility of the event are shown in Fig BelowTotal Lunar Eclipse of December 10. The timings of the major eclipse phases are listed below.
Penumbral Eclipse Begins:   11:33:32 UT
   Partial Eclipse Begins:     12:45:42 UT
   Total Eclipse Begins:       14:06:16 UT
   Greatest Eclipse:           14:31:49 UT
   Total Eclipse Ends:         14:57:24 UT
   Partial Eclipse Ends:       16:17:58 UT
   Penumbral Eclipse Ends:     17:30:00 UT

Total Lunar Eclipse December 2011
At the instant of greatest eclipse (14:32 UT) the Moon lies at the zenith in the Pacific Ocean near Guam and the Northern Mariana Islands. The umbral eclipse magnitude peaks at 1.1061 as the Moon's centre passes 21.4 arc-minutes south of the shadow axis. The Moon's northern limb is then 6.4 arc-minutes south of the shadows axis and 33.3 arc-minutes from the umbra's edge. In contrast, the Moon's southern limb lays 36.5 arc-minutes from the shadow centre and 3.2 arc-minutes from the southern edge of the umbra. Thus, the northern half of the Moon will appear much darker than the southern half because it lies deeper in the umbra.

Since the Moon samples a large range of umbral depths during totality, its appearance will change dramatically with time. It is difficult to predict the brightness distribution in the umbra, so observers are encouraged to estimate the Danjon value at different times during totality (see Danjon Scale of Lunar Eclipse Brightness). Note that it may also be necessary to assign different Danjon values to different portions of the Moon (i.e., north vs. south). 

During totality, the winter constellations are well placed for viewing so a number of bright stars can be used for magnitude comparisons. Aldebaran (mv = +0.87) is 9° to the southwest of the eclipsed Moon, while Betelgeuse (mv = +0.45) is 19° to the southeast, Pollux (mv = +1.16) is 37° east, and Capella (mv = +0.08) is 24° north. 

The entire event is visible from Asia and Australia. For North Americans, the eclipse is in progress as the Moon sets with western observers favored by a larger fraction of the eclipse before moonset. Observers throughout Europe and Africa will miss the early eclipse phases because they occur before moonrise. None of the eclipse can be seen from South America or Antarctica. The NASA JavaScript Lunar Eclipse Explorer is an interactive web page that can quickly calculate the altitude of the Moon during each phase of the eclipse from any geographic location:
 
Table 6 lists predicted umbral immersion and emersion times for 20 well-defined lunar craters. The timing of craters is useful in determining the atmospheric enlargement of Earth's shadow (see Crater Timings During Lunar Eclipses). 

The December 10 total lunar eclipse is the 23rd member of Saros 135, a series of 71 eclipses occurring in the following order: 9 penumbral, 10 partial, 23 total, 7 partial, and 22 penumbral lunar eclipses. Complete details for Saros 135 can be found at: 


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Eclipsed Moon in the Morning

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Tomorrow, December 10, the Full Moon will slide through planet Earth's shadow in a total lunar eclipse. The entire eclipse sequence, including 51 minutes of totality, will be visible from Asia and Australia, but moonwatchers in Europe and Africa will miss out on the beginning partial phases because for them, the eclipse will start before moonrise. In central and western North America the earlier phases of the eclipse will be in progress as the Moon sets. In fact, while those in the east will miss out, North Americans far enough west could see a scene very much like this one, with a mostly eclipsed Moon low and near the western horizon during morning twilght. This morning twilight view of another lunar eclipse approaching its total phase at moonset was captured in 2008 on February 21, from the Zagros Mountains of Iran.

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Thursday, December 8, 2011

Sh2-239: Celestial Impasto

Thursday, December 8, 2011
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The cosmic brush of star formation composed this alluring mix of dust and dark nebulae. Cataloged as Sh2-239 and LDN 1551, the region lies near the southern end of the Taurus molecular cloud complex some 450 light-years distant. Stretching for nearly 3 light-years, the canvas abounds with signs of embedded young stellar objects driving dynamic outflows into the surrounding medium. Included near the center of the frame, a compact, tell-tale red jet of shocked hydrogen gas is near the position of infrared source IRS5, known to be a system of protostars surrounded by dust disks. Just below it are the broader, brighter wings of HH 102, one of the region's many Herbig-Haro objects, nebulosities associated with newly born stars. Estimates indicate that the star forming LDN 1551 region contains a total amount of material equivalent to about 50 times the mass of the Sun.

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Wednesday, December 7, 2011

Kepler 22b: An Almost Earth Orbiting an Almost Sun

Wednesday, December 7, 2011
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It’s the closest match to Earth that has yet been found. Recently discovered planet Kepler 22b has therefore instantly become the best place to find life outside our Solar System. The planet's host star, Kepler 22, is actually slightly smaller and cooler than the Sun, and lies 600 light-years from Earth toward the constellation of the Swan (Cygnus). The planet, Kepler 22b, is over twice the radius of the Earth and orbits slightly closer in, but lies in the habitable zone where liquid water could exist on the surface. Pictured above is an artist’s depiction of how Kepler 22b might appear to an approaching spaceship, in comparison to the inner planets of our Solar System. Whether Kepler 22b actually contains water or life is currently unknown. A SETI project, however, will begin monitoring Kepler 22b for signs of intelligence.

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Tuesday, December 6, 2011

NASA discovers new earth 'Kepler-22b'

Tuesday, December 6, 2011
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NASA has confirmed the existence of an earth-like planet circling a star, 600 light years away from us.

Planet found orbiting habitable zone of sun-like star

 The most Earth-like planet ever discovered is circling a star 600 light years away, a key finding in an ongoing quest to learn if life exists beyond Earth, scientists said on Monday.

The planet, called Kepler-22b, joins a list of more than 500 planets found to orbit stars beyond our solar system. It is the smallest and the best positioned to have liquid water on its surface -- among the ingredients necessary for life on Earth.

The planet contains both land and water and has a "similar temperature to that of the Earth" of around 72 degrees (22 Celsius).

It is 2.4 times the size of Earth and has a slightly shorter orbit than our planet, of 290 days.

There are now three planets outside the system, known as exoplanets, which experts believe could potentially be colonised by future generations.

In May, French astronomers identified Gliese 581d, pronounced “gleezer”, which is far closer at around 20 light years away.

It is about six times the mass of Earth and is one of a family of at least six planets.

In August, a team from Switzerland reported that another planet 36 light years away called HD 85512b seemed to be habitable.

The planet is in the constellation of Vela, and measures around 3.6 times the Earth's mass.

"We are homing in on the true Earth-sized, habitable planets," said San Jose State University astronomer Natalie Batalha, deputy science team lead for NASA's Kepler Space Telescope that discovered the star.

The telescope, which was launched three years ago, is staring at about 150,000 stars in the constellations Cygnus and Lyra, looking for faint and periodic dimming as any circling planets pass by, relative to Kepler's line of sight.

Results will be extrapolated to determine the percentage of stars in the Milky Way galaxy that harbor potentially habitable, Earth-size planets.

This is the first detection of a potentially habitable world orbiting a Sun-like star, scientists reported in findings to be published in The Astrophysical Journal.

Kepler-22b is 600 light years away. A light year is the distance light travels in a year, about 6 trillion miles (10 trillion km).


GROUND TELESCOPES

Planets about the same distance from their parent stars as Earth take roughly a year to complete an orbit. Scientists want to see at least three transits to be able to rule out other explanations for fluctuations in a star's light, such as small companion stars. Results also are verified by ground and other space telescopes.

Kepler-22b, which is about 2.4 times the radius of Earth, sits squarely in its star's so-called "habitable zone," the region where liquid water could exist on the surface. Follow-up studies are under way to determine if the planet is solid, like Earth, or more gaseous like Neptune.

"We don't know anything about the planets between Earth-size and Neptune-size because in our solar system we have no examples of such planets. We don't know what fraction are going to be rocky, what fraction are going to be water worlds, what fraction are ice worlds. We have no idea until we measure one and see," Batalha said at a news conference at NASA Ames Research Center in Moffet Field, California.

If Kepler-22b has a surface and a cushion of atmosphere similar to Earth's, it would be about 72 degrees Fahrenheit (22 C), about the same as a spring day in Earth's temperate zone.

Among the 2,326 candidate planets found by the Kepler team, 10 are roughly Earth-size and reside in their host stars' habitable zones.

Another team of privately funded astronomers is scanning the target stars for non-naturally occurring radio signals, part of a project known as SETI, or the Search for Extraterrestrial Intelligence.

"As soon as we find a different, a separate, an independent example of life somewhere else, we're going to know that it's ubiquitous throughout the universe," said astronomer Jill Tarter, director of the SETI Institute in Mountain View.

The Kepler team is meeting for its first science conference this week.

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Monday, December 5, 2011

Jupiter Rotation Movie from Pic du Midi

Monday, December 5, 2011
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Observe the graceful twirl of the Solar System's largest planet. Many interesting features of Jupiter's enigmatic atmosphere, including dark bands and light zones, can be followed in detail. A careful inspection will reveal that central clouds rotate slightly faster than clouds toward the poles. The famous Great Red Spot is visible at first but soon rotates out of view, only to return near the movie's end. Other smaller storm systems ocassionally appear. As large as Jupiter is, it rotates in only 10 hours. Our small Earth, by comparison, takes 24 hours to complete a spin cycle. The above high-resolution time-lapse movie was captured over the past year by the one-meter Telescope at the Pic du Midi Observatory in the French Pyrenees. Since hydrogen and helium gas are colorless, and those elements compose most of Jupiter's expansive atmosphere, what trace elements create the observed colors of Jupiter's clouds remains unknown.

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Kepler-22b, Super-Earth in the habitable zone of a Sun-like Star

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 The Kepler Science Conference is happening Dec 5 through 9.
Watch it online at: http://connect.arc.nasa.gov/kepler


This image is an artist's conception of planet Kepler-22b, a planet known to comfortably circle in the habitable zone of a sun-like star. It is the first planet that NASA's Kepler mission has confirmed to orbit in a star's habitable zone -- the region around a star where liquid water, a requirement for life on Earth, could persist. The planet is 2.4 times the size of Earth, making it the smallest yet found to orbit in the middle of the habitable zone of a star like our sun.

Scientists do not yet know if the planet has a predominantly rocky, gaseous, or liquid composition. It's possible that the world would have clouds in its atmosphere, as depicted here in the artist's interpretation.
Kepler also has discovered more than 1,000 new planet candidates, nearly doubling its previously known count. Ten of these candidates are near-Earth-size and orbit in the habitable zone of their host star. Since the last catalog was released in February, the number of planet candidates identified by Kepler has increased by 89 percent and now totals 2,326. Of these, 207 are approximately Earth-size, 680 are super Earth-size, 1,181 are Neptune-size, 203 are Jupiter-size and 55 are larger than Jupiter. The number of Earth-size and super Earth-size candidates has increased by more than 200 and 140 percent since February, respectively. There are 48 planet candidates in their star's habitable zone, a decrease from the 54 reported in February, because the Kepler team has applied a stricter definition of what constitutes a habitable zone in the new catalog, to account for the warming effect of atmospheres, which would move the zone away from the star, out to longer orbital periods.

Quotes from Kepler team:

"This is a major milestone on the road to finding Earth's twin," said Douglas Hudgins, Kepler program scientist at NASA Headquarters in Washington. "Kepler's results continue to demonstrate the importance of NASA's science missions, which aim to answer some of the biggest questions about our place in the universe."


"Fortune smiled upon us with the detection of this planet," said William Borucki, Kepler principal investigator at NASA Ames Research Center at Moffett Field, Calif., who led the team that discovered Kepler-22b. "The first transit was captured just three days after we declared the spacecraft operationally ready. We witnessed the defining third transit over the 2010 holiday season."

"The tremendous growth in the number of Earth-size candidates tells us that we're honing in on the planets Kepler was designed to detect: those that are not only Earth-size, but also are potentially habitable," said Natalie Batalha, Kepler deputy science team lead at San Jose State University in California. "The more data we collect, the keener our eye for finding the smallest planets out at longer orbital periods."

This diagram below compares our own solar system to Kepler-22. The diagram includes the habitable zone where water can exist in liquid form. Kepler-22's star is a bit smaller than our sun, so it's habitable zone is slightly closer in. The orbit of Kepler-22b around its star takes 289 days and is about 85% as large as Earth's orbit.

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A Memorable Aurora Over Norway

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It was one of the most memorable auroras of the season. There was green light, red light, and sometimes a mixture of the two. There were multiple rays, distinct curtains, and even an auroral corona. It took up so much of the sky. In the background were stars too numerous to count, in the foreground a friend trying to image the same sight. The scene was captured with a fisheye lens around and above Tromsø, Norway, last month. With the Sun becoming more active, next year might bring even more spectacular aurora.

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Sunday, December 4, 2011

Light Echoes from V838 Mon

Sunday, December 4, 2011
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For reasons unknown, star V838 Mon's outer surface suddenly greatly expanded with the result that it became the brightest star in the entire Milky Way Galaxy in January 2002. Then, just as suddenly, it faded. A stellar flash like this has never been seen before. It's true that supernovae and novae expel matter out into space. But while the V838 Mon flash appears to expel material into space, what is seen here is actually an outwardly moving light echo of the bright flash. In a light echo, light from the flash is reflected by successively more distant rings in the ambient interstellar dust that already surrounded the star. V838 Mon lies about 20,000 light years away toward the constellation of Monoceros the unicorn. In this Hubble Space Telescope image from February 2004, the light echo is about six light years in diameter.

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Saturday, December 3, 2011

As Above, So Below

Saturday, December 3, 2011
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A single, long exposure captured these star trails above a remarkably colorful sea of clouds. As seen from Medvednica mountain, the surrounding peaks and lights illuminating the clouds from below are north of Zagreb, Croatia. Near the center of the also colorful star trail arcs, the North Celestial Pole is off the upper right edge of the frame. Even though this is the age of the digital camera, the well composed skyscape was recorded using color slide film in a medium format camera. The dreamlike scene's starry sky and ephemeral ocean could be reminiscent of an older age still, when the Pannonian Sea covered this part of central Europe some 10 million years ago.

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Friday, December 2, 2011

Solar Eclipse over Antarctica

Friday, December 2, 2011
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Last Friday, the fourth and final partial solar eclipse of 2011 was only visible from high latitudes in the southern hemisphere. If you missed it, check out this dramatic picture of the geocentric celestial event from a very high southern latitude on the continent of Antarctica. From a camera positioned at San Martín Station (Argentina) near the antarctic peninsula mountain range, the picture looks toward the south and east. The Sun and silhouetted lunar disk are seen through thin, low clouds. Perhaps fittingly, the mountainous slope in the foreground is part of the larger Roman Four Promontory, named for its craggy, snow covered face that resembles the Roman numeral IV. For 2011, there is actually one more eclipse to go, a total eclipse of the Moon. Parts of that eclipse will be visible from most of planet Earth (but not Antarctica ...) on December 10.

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Thursday, December 1, 2011

Young Moon Meets Evening Star

Thursday, December 1, 2011
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Now appearing as planet Earth's evening star, brilliant Venus shines in western skies at twilight. Standing above a rugged horizon and warm sunset colors, the twilight's celestial beacon was joined last Saturday by a Moon 35 hours young in this gorgeous skyscape. The close pairing of Venus and Moon is known as a conjunction. Not visible in the frame, fleeting planet Mercury has fallen from evening skies, sinking deeper into the sunset glow below the young crescent Moon. The scene was captured while trekking in northern Portugal's Peneda-Geres National Park.

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Monday, October 31, 2011

Ghost of the Cepheus Flare

Monday, October 31, 2011
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Spooky shapes seem to haunt this starry expanse, drifting through the night in the royal constellation Cepheus. Of course, the shapes are cosmic dust clouds faintly visible in dimly reflected starlight. Far from your own neighborhood on planet Earth, they lurk at the edge of the Cepheus Flare molecular cloud complex some 1,200 light-years away. Over 2 light-years across the ghostly nebula and relatively isolated Bok globule, also known as vdB 141 or Sh2-136, is near the center of the field. The core of the dark cloud on the right is collapsing and is likely a binary star system in the early stages of formation. Even so, if the spooky shapes could talk, they might well wish you a happy Halloween.

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Sunday, October 30, 2011

White Rock Fingers on Mars

Sunday, October 30, 2011
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What caused this unusual light rock formation on Mars? Intrigued by the possibility that they could be salt deposits left over as an ancient lakebed dried-up, detailed studies of these fingers now indicate a more mundane possibility: volcanic ash. Studying the exact color of the formation indicated the possible volcanic origin. The light material appears to have eroded away from surrounding area, indicating a very low-density substance. The stark contrast between the rocks and the surrounding sand is compounded by the unusual darkness of the sand. The above picture was taken with the Thermal Emission Imaging System on the Mars Odyssey spacecraft currently orbiting Mars. The image spans about 10 kilometers inside a larger crater.

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Saturday, October 29, 2011

Spiral Galaxy NGC 3370 from Hubble

Saturday, October 29, 2011
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Is this what our own Milky Way Galaxy looks like from far away? Similar in size and grand design to our home Galaxy (although without the central bar), spiral galaxy NGC 3370 lies about 100 million light-years away toward the constellation of the Lion (Leo). Recorded above in exquisite detail by the Hubble Space Telescope's Advanced Camera for Surveys, the big, beautiful face-on spiral is not only photogenic, but has proven sharp enough to study individual stars known as Cepheids. These pulsating stars have been used to accurately determine NGC 3370's distance. NGC 3370 was chosen for this study because in 1994 the spiral galaxy was also home to a well studied stellar explosion -- a Type Ia supernova. Combining the known distance to this standard candle supernova, based on the Cepheid measurements, with observations of supernovas at even greater distances, has helped to reveal the size and expansion rate of the entire Universe itself.

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Friday, October 28, 2011

October Skylights

Friday, October 28, 2011
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As northern hemisphere nights grow longer, October is a good month for spotting auroras, or even other eerie apparitions after dark. And this week the night sky did not disappoint. On October 24th a solar coronal mass ejection impacted planet Earth's magnetosphere triggering far ranging auroral displays. On that night, this dramatic silhouette against deep red and beautiful green curtains of shimmering light was captured near Whitby, Ontario, Canada. But auroras were reported even farther south, in US states like Alabama, Kansas, and Oklahoma at latitudes rarely haunted by the northern lights. Well above 100 kilometers, at the highest altitudes infused by the auroral glow, the red color comes from the excitation of oxygen atoms.

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Thursday, October 27, 2011

Young Suns of NGC 7129

Thursday, October 27, 2011
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Young suns still lie within dusty NGC 7129, some 3,000 light-years away toward the royal constellation Cepheus. While these stars are at a relatively tender age, only a few million years old, it is likely that our own Sun formed in a similar stellar nursery some five billion years ago. Most noticeable in the sharp image are the lovely bluish dust clouds that reflect the youthful starlight. But the compact, deep red crescent shapes are also markers of energetic, young stellar objects. Known as Herbig-Haro objects, their shape and color is characteristic of glowing hydrogen gas shocked by jets streaming away from newborn stars. Paler, extended filaments of reddish emission mingling with the bluish clouds are caused by dust grains effectively converting the invisible ultraviolet starlight to visible red light through photoluminesence. Ultimately the natal gas and dust in the region will be dispersed, the stars drifting apart as the loose cluster orbits the center of the Galaxy. At the estimated distance of NGC 7129, this telescopic view spans about 40 light-years.

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Wednesday, October 26, 2011

In, Through, and Beyond Saturn's Rings

Wednesday, October 26, 2011
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A fourth moon is visible on the above image if you look hard enough. First -- and farthest in the background -- is Titan, the largest moon of Saturn and one of the larger moons in the Solar System. The dark feature across the top of this perpetually cloudy world is the north polar hood. The next most obvious moon is bright Dione, visible in the foreground, complete with craters and long ice cliffs. Jutting in from the left are several of Saturn's expansive rings, including Saturn's A ring featuring the dark Encke Gap. On the far right, just outside the rings, is Pandora, a moon only 80-kilometers across that helps shepherd Saturn's F ring. The fourth moon? If you look closely in the Encke Gap you'll find a speck that is actually Pan. Although one of Saturn's smallest moons at 35-kilometers across, Pan is massive enough to help keep the Encke gap relatively free of ring particles.

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Tuesday, October 25, 2011

IC 1805: The Heart Nebula in HDR

Tuesday, October 25, 2011
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What powers the Heart Nebula? The large emission nebula dubbed IC 1805 looks, in whole, like a human heart. The nebula glows brightly in red light emitted by its most prominent element: hydrogen. The red glow and the larger shape are all created by a small group of stars near the nebula's center. A close up in high dynamic range (HDR) spanning about 30 light years contains many of these stars is shown above. This open cluster of stars contains a few bright stars nearly 50 times the mass of our Sun, many dim stars only a fraction of the mass of our Sun, and an absent microquasar that was expelled millions of years ago. The Heart Nebula is located about 7,500 light years away toward the constellation of Cassiopeia.

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Monday, October 24, 2011

HH-222: The Waterfall Nebula

Monday, October 24, 2011
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What created the Waterfall Nebula? No one knows. The structure seen in the region of NGC 1999 in the Great Orion Molecular Cloud complex is one of the more mysterious structures yet found on the sky. Designated HH-222, the elongated gaseous stream stretches about ten light years and emits an unusual array of colors. One hypothesis is that the gas filament results from the wind from a young star impacting a nearby molecular cloud. That would not explain, however, why the Waterfall and fainter streams all appear to converge on a bright but unusual non thermal radio source located toward the upper left of the curving structure. Another hypothesis is that the unusual radio source originates from a binary system containing a hot white dwarf, neutron star, or black hole, and that the Waterfall is just a jet from this energetic system. Such systems, though, are typically strong X-rays emitters, and no X-rays have been detected. For now, this case remains unsolved. Perhaps well-chosen future observations and clever deductive reasoning will unlock the true origin of this enigmatic wisp in the future.

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Sunday, October 23, 2011

Jupiter's Clouds from New Horizons

Sunday, October 23, 2011
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The New Horizons spacecraft took some stunning images of Jupiter on its way out to Pluto. Famous for its Great Red Spot, Jupiter is also known for its regular, equatorial cloud bands, visible through even modest sized telescopes. The above image, horizontally compressed, was taken in 2007 near Jupiter's terminator and shows the Jovian giant's wide diversity of cloud patterns. On the far left are clouds closest to Jupiter's South Pole. Here turbulent whirlpools and swirls are seen in a dark region, dubbed a belt, that rings the planet. Even light colored regions, called zones, show tremendous structure, complete with complex wave patterns. The energy that drives these waves surely comes from below. New Horizons is the fastest space probe ever launched, has now passed the orbits of Saturn and Uranus and is on track to reach Pluto in 2015.

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Saturday, October 22, 2011

Jupiter Near Opposition

Saturday, October 22, 2011
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On October 29 (UT), Jupiter, the solar system's largest planet, will be at opposition, opposite the Sun in planet Earth's sky, shining brightly and rising as the Sun sets. That configuration results in Jupiter's almost annual closest approach to planet Earth, so near opposition the gas giant offers earthbound telescopes stunning views of its stormy, banded atmosphere and large Galilean moons. This sharp snapshot of Jupiter was captured on October 13 with the 1 meter telescope at the Pic Du Midi mountain top observatory in the French Pyrenees. North is up in the image that shows off oval shaped vortices and planet girdling dark belts and light zones. Also seen in remarkable detail, Jupiter's icy Ganymede, the solar system's largest moon, is emerging from behind the planet (top) while volcanic Io enters the frame near the lower left edge

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Friday, October 21, 2011

Clouds of Perseus

Friday, October 21, 2011
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Cosmic clouds of gas and dust drift across this magnificent panorama, spanning some 17 degrees near the southern boundary of the heroic constellation Perseus. The collaborative skyscape begins with bluish stars of Perseus at the left, but the eye is drawn to the striking, red NGC 1499. Also known as the California Nebula, its characteristic glow of atomic hydrogen gas is powered by ultraviolet light from luminous blue star Xi Persei immediately to the nebula's right. Farther along, intriguing young star cluster IC 348 and neighboring Flying Ghost Nebula are right of center. Connected by dark and dusty tendrils on the outskirts of a giant molecular cloud, another active star forming region, NGC 1333, lies near the upper right edge of the wide field of view. Shining faintly, dust clouds strewn throughout the scene are hovering hundreds of light-years above the galactic plane and reflect starlight from the Milky Way.

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Thursday, October 20, 2011

Tails of Comet Garradd

Thursday, October 20, 2011
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A good target for binoculars and small telescopes, Comet Garradd (C/2009 P1) now shines in planet Earth's evening skies, a steady performer but just below naked-eye visibility. Telescopic images like this composite from October 15 can find the comet with a lovely green coma, sporting multiple tails, and lingering against a background of faint stars. The field of view spans over 1 degree or about 2 full moons within the southern boundaries of the constellation Hercules. Now around 16 light minutes (2 astronomical units) away, P1 Garradd is an intrinsically large comet, but will never make a very close approach to Earth or the Sun while sweeping through the inner solar system. As a result, the comet will likely stay a sight for telescopic eyes only, moving slowly through the sky and remaining in Hercules during the coming months.

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Wednesday, October 19, 2011

Draconid Meteors Over Spain

Wednesday, October 19, 2011
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What are those streaks in the sky? They're meteors from the Draconids meteor shower that peaked earlier this month. The above composite image captured numerous meteor streaks over 90 minutes above the Celtic ruins of Capote in Badajoz province, Spain. The particles that caused these meteors were typically the size of a pebble and were expelled long ago from the nucleus of comet 21P/Giacobini-Zinner. Most of the above meteors can be traced back to a single radiant emanating from the constellation of the Dragon (Draco). Reports from this year's meteor shower indicate that the Draconids were unusually good this year with activity was concentrated around 8 pm UT on October 8. The most intense Draconid meteor showers in recent history occurred in 1933 and 1946 when thousands of meteors per hour were recorded as the Earth plowed through particularly dense streams of comet debris. Although the Draconids occur every October, it is usually difficult to know just how active each year's meteor shower will be.

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Tuesday, October 18, 2011

Movie: Approaching Light Speed

Tuesday, October 18, 2011
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What would it look like to travel near the speed of light? Strange visual effects would appear as documented in the above relativistically-accurate animation. First of all, relativistic aberration would cause objects to appear to bunch up in front you. Next, the Doppler shift would cause the colors of forward objects to shift toward the blue, while things behind you would shift toward the red. Similarly, the world in front of you would seem to move unusually fast, while the world behind you would appear to slow down. Objects to the sides will appear rotated, possibly enabling surfaces normally hidden from you to become visible. Of course, since constant motion is relative, the same effects would occur were you to remain stationary and the entire world advanced toward you.

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Monday, October 17, 2011

MACS 1206: A Galaxy Cluster Gravitational Lens

Monday, October 17, 2011
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It is difficult to hide a galaxy behind a cluster of galaxies. The closer cluster's gravity will act like a huge lens, pulling images of the distant galaxy around the sides and greatly distorting them. This is just the case observed in the above recently released image from the CLASH survey with the Hubble Space Telescope. The cluster MACS J1206.2-0847 is composed of many galaxies and is lensing the image of a yellow-red background galaxy into the huge arc on the right. Careful inspection of the image will reveal at least several other lensed background galaxies -- many appearing as elongated wisps. The foreground cluster can only create such smooth arcs if most of its mass is smoothly distributed dark matter -- and therefore not concentrated in the cluster galaxies visible. Analyzing the positions of these gravitational arcs also gives astronomers a method to estimate the dark matter distribution in galaxy clusters, and infer from that when these huge conglomerations of galaxies began to form.

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Sunday, October 16, 2011

A Picturesque Venus Transit

Sunday, October 16, 2011
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The rare transit of Venus across the face of the Sun in 2004 was one of the better-photographed events in sky history. Both scientific and artistic images flooded in from the areas that could see the transit: Europe and much of Asia, Africa, and North America. Scientifically, solar photographers confirmed that the black drop effect is really better related to the viewing clarity of the camera or telescope than the atmosphere of Venus. Artistically, images might be divided into several categories. One type captures the transit in front of a highly detailed Sun. Another category captures a double coincidence such as both Venus and an airplane simultaneously silhouetted, or Venus and the International Space Station in low Earth orbit. A third image type involves a fortuitous arrangement of interesting looking clouds, as shown by example in the above image taken from North Carolina, USA. The next transit of Venus across the Sun will be in 2012 June.

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