martes, 21 de octubre de 2014

APOD - Mimas: Small Moon with a Big Crater

Astronomy Picture of the Day

Discover the cosmos! Each day a different image or photograph of our fascinating universe is featured, along with a brief explanation written by a professional astronomer.

2014 October 21
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Mimas: Small Moon with a Big Crater
Image Credit: Cassini Imaging Team, ISS, JPL, ESA, NASA; Digital Processing: Supportstorm

Explanation: Whatever hit Mimas nearly destroyed it. What remains is one of the largest impact craters on one of Saturn's smallest moons. The crater, named Herschel after the 1789 discoverer of Mimas, Sir William Herschel, spans about 130 kilometers and is pictured above. Mimas' low mass produces a surface gravity just strong enough to create a spherical body but weak enough to allow such relatively large surface features. Mimas is made of mostly water ice with a smattering of rock - so it is accurately described as a big dirty snowball. The above image was taken during the 2005 August flyby of the robot spacecraft Cassini now in orbit around Saturn. A recent analysis of Mimas's unusual wobble indicates that it might house a liquid water interior ocean.

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Tomorrow's picture: open space


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lunes, 20 de octubre de 2014

APOD - Comet Siding Spring Passes Mars

Astronomy Picture of the Day

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2014 October 20
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Comet Siding Spring Passes Mars
Image Credit & Copyright: SEN/Damian Peach

Explanation: Yesterday, a comet passed very close to Mars. In fact, Comet C/2013 A1 (Siding Spring) passed closer to the red planet than any comet has ever passed to Earth in recorded history. To take advantage of this unique opportunity to study the close interaction of a comet and a planet, humanity currently has five active spacecraft orbiting Mars: NASA's MAVEN, MRO, Mars Odyssey, as well as ESA's Mars Express, and India's Mars Orbiter. Most of these spacecraft have now sent back information that they have not been damaged by small pieces of the passing comet. These spacecraft, as well as the two active rovers on the Martian surface -- NASA's Opportunity and Curiosity -- have taken data and images that will be downloaded to Earth for weeks to come and likely studied for years to come. The featured image taken yesterday, however, was not taken from Mars but from Earth and shows Comet Siding Spring on the lower left as it passed Mars, on the upper right.

NASA Updates : Comet Siding Spring from Mars
Tomorrow's picture: yes, that is a moon


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domingo, 19 de octubre de 2014

APOD - Comet McNaught Over New Zealand

Astronomy Picture of the Day

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2014 October 19
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Comet McNaught Over New Zealand
Image Credit & Copyright: Minoru Yoneto

Explanation: Comet McNaught was perhaps the most photogenic comet of modern times -- from Earth. After making quite a show in the northern hemisphere in early January of 2007, the comet moved south and developed a long and unusual dust tail that dazzled southern hemisphere observers. In late January 2007, Comet McNaught was captured between Mount Remarkable and Cecil Peak in this spectacular image taken from Queenstown, South Island, New Zealand. The bright comet dominates the right part of the above image, while the central band of our Milky Way Galaxy dominates the left. Careful inspection of the image will reveal a meteor streak just to the left of the comet. Today, Comet Siding Spring may become the most photogenic comet of modern times -- from Mars.

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Tomorrow's picture: yes, that's a moon


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sábado, 18 de octubre de 2014

APOD - Melotte 15 in the Heart

Astronomy Picture of the Day

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2014 October 18
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Melotte 15 in the Heart
Image Credit & Copyright: Ivan Eder

Explanation: Cosmic clouds form fantastic shapes in the central regions of emission nebula IC 1805. The clouds are sculpted by stellar winds and radiation from massive hot stars in the nebula's newborn star cluster, Melotte 15. About 1.5 million years young, the cluster stars are toward the right in this colorful skyscape, along with dark dust clouds in silhouette against glowing atomic gas. A composite of narrowband and broadband telescopic images, the view spans about 30 light-years and includes emission from ionized hydrogen, sulfur, and oxygen atoms mapped to green, red, and blue hues in the popular Hubble Palette. Wider field images reveal that IC 1805's simpler, overall outline suggests its popular name - The Heart Nebula. IC 1805 is located about 7,500 light years away toward the boastful constellation Cassiopeia.

Tomorrow's picture: photogenic comets


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viernes, 17 de octubre de 2014

APOD - Messier 6 and Comet Siding Spring

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2014 October 17
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Messier 6 and Comet Siding Spring
Image Credit & Copyright: Rolando Ligustri (CARA Project, CAST)

Explanation: This looks like a near miss but the greenish coma and tail of Comet Siding Spring (C/2013 A1) are really 2,000 light-years or so away from the stars of open cluster Messier 6. They do appear close together though, along the same line-of-sight in this gorgeous October 9th skyscape toward the constellation Scorpius. Still, on Sunday, October 19th this comet really will be involved in a near miss, passing within only 139,500 kilometers of planet Mars. That's about 10 times closer than any known comet flyby of planet Earth, and nearly one third the Earth-Moon distance. While an impact with the nucleus is not a threat the comet's dust, moving with a speed of about 56 kilometers per second relative to the Red Planet, and outskirts of its gaseous coma could interact with the thin Martian atmosphere. Of course, the comet's close encounter will be followed intently by spacecraft in Martian orbit and rovers on the surface.

Tomorrow's picture: light-weekend


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Authors & editors: Robert Nemiroff (MTU) & Jerry Bonnell (UMCP)
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