Juana Santana

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APOD: Cassini Spacecraft Crosses Saturn's Ring Plane (2014 Feb 23) Image Credit: Cassini Imaging Team, ISS, JPL, ESA, NASA http://apod.nasa.gov/apod/ap140223.html Explanation: If this is Saturn, where are the rings? When Saturn's "appendages" disappeared in 1612, Galileo did not understand why. Later that century, it became understood that Saturn's unusual protrusions were rings and that when the Earth crosses the ring plane, the edge-on rings will appear to disappear. This is because Saturn's rings are confined to a plane many times thinner, in proportion, than a razor blade. In modern times, the robot Cassini spacecraft orbiting Saturn now also crosses Saturn's ring plane. A series of plane crossing images from 2005 February was dug out of the vast online Cassini raw image archive by interested Spanish amateur Fernando Garcia Navarro. Pictured above, digitally cropped and set in representative colors, is the striking result. Saturn's thin ring plane appears in blue, bands and clouds in Saturn's upper atmosphere appear in gold. Details of Saturn's rings can be seen in the high dark shadows across the top of this image, taken back in 2005. Moons appear as bumps in the rings. http://ciclops.org/ http://spacescience.org/ http://saturn.jpl.nasa.gov/ http://www.esa.int/ http://www.nasa.gov/ Starship Asterisk* • APOD Discussion Page http://asterisk.apod.com/discuss_apod.php?date=140223 #APOD

APOD: NGC 7331 and Beyond (2014 Mar 01) Image Credit & Copyright: Dietmar Hager, Torsten Grossmann http://apod.nasa.gov/apod/ap140301.html Explanation: Big, beautiful spiral galaxy NGC 7331 is often touted as an analog to our own Milky Way. About 50 million light-years distant in the northern constellation Pegasus, NGC 7331 was recognized early on as a spiral nebula and is actually one of the brighter galaxies not included in Charles Messier's famous 18th century catalog. Since the galaxy's disk is inclined to our line-of-sight, long telescopic exposures often result in an image that evokes a strong sense of depth. The effect is further enhanced in this sharp image by galaxies that lie beyond the gorgeous island universe. The background galaxies are about one tenth the apparent size of NGC 7331 and so lie roughly ten times farther away. Their close alignment on the sky with NGC 7331 occurs just by chance. Seen here through faint foreground dust clouds lingering above the plane of Milky Way, this visual grouping of galaxies is also known as the Deer Lick Group. http://www.stargazer-observatory.com/ http://astrogrossi.de/ Starship Asterisk* • APOD Discussion Page http://asterisk.apod.com/discuss_apod.php?date=140301 #APOD

APOD: Martian Sunset (2014 Mar 02) Image Credit: Mars Exploration Rover Mission, Texas A&M, Cornell, JPL, NASA http://apod.nasa.gov/apod/ap140302.html Explanation: What would it be like to see a sunset on Mars? To help find out, the robotic rover Spirit was deployed in 2005 to park and watch the Sun dip serenely below the distant lip of Gusev crater. Colors in the above image have been slightly exaggerated but would likely be apparent to a human explorer's eye. Fine martian dust particles suspended in the thin atmosphere lend the sky a reddish color, but the dust also scatters blue light in the forward direction, creating a bluish sky glow near the setting Sun. Because Mars is farther away, the Sun is less bright and only about two thirds the diameter it appears from Earth. Images like this help atmospheric scientists understand not only the atmosphere of Mars, but atmospheres across the Solar System, including our home Earth. http://marsrovers.jpl.nasa.gov/ http://physics.tamu.edu/ http://athena.cornell.edu/ http://www.jpl.nasa.gov/ Starship Asterisk* • APOD Discussion Page http://asterisk.apod.com/discuss_apod.php?date=140302 #APOD

APOD: Habitable Worlds (2014 Mar 03) Image Credit & Licence: Planetary Habitability Laboratory (UPR Arecibo) http://apod.nasa.gov/apod/ap140303.html Explanation: Is Earth the only known world that can support life? In an effort to find life-habitable worlds outside our Solar System, stars similar to our Sun are being monitored for slight light decreases that indicate eclipsing planets. Many previously-unknown planets are being found, including over 700 worlds recently uncovered by NASA's Kepler satellite. Depicted above in artist's illustrations are twelve extrasolar planets that orbit in the habitable zones of their parent stars. These exoplanets have the right temperature for water to be a liquid on their surfaces, and so water-based life on Earth might be able to survive on them. Although technology cannot yet detect resident life, finding habitable exoplanets is a step that helps humanity to better understand its place in the cosmos. http://phl.upr.edu/ http://www.upra.edu/ Starship Asterisk* • APOD Discussion Page http://asterisk.apod.com/discuss_apod.php?date=140303 #APOD

APOD: Globules in the Running Chicken Nebula (2014 Mar 05) Image Credit & Copyright: Fred Vanderhaven http://apod.nasa.gov/apod/ap140305.html Explanation: The eggs from this chicken may form into stars. The above pictured emission nebula, cataloged as IC 2944, is called the Running Chicken Nebula for the shape of its greater appearance. The image was taken recently from Siding Spring Observatory in Australia and presented in scientifically assigned colors. Seen near the center of the image are small, dark molecular clouds rich in obscuring cosmic dust. Called Thackeray's Globules for their discoverer, these "eggs" are potential sites for the gravitational condensation of new stars, although their fates are uncertain as they are also being rapidly eroded away by the intense radiation from nearby young stars. Together with patchy glowing gas and complex regions of reflecting dust, these massive and energetic stars form the open cluster Collinder 249. This gorgeous skyscape spans about 70 light-years at the nebula's estimated 6,000 light-year distance. http://fredsastro.smugmug.com/ Starship Asterisk* • APOD Discussion Page http://asterisk.apod.com/discuss_apod.php?date=140305 #APOD

APOD: Sun and Prominence (2014 Mar 04) Image Credit & Copyright: jp-Brahic http://apod.nasa.gov/apod/ap140304.html Explanation: Dramatic prominences can sometimes be seen looming just beyond the edge of the sun. Such was the case last week as a large prominence, visible above, highlighted a highly active recent Sun. A waving sea of hot gas is visible in the foreground chromosphere in great detail as it was imaged in one specific color of light emitted by hydrogen. A solar prominence is a cloud of solar gas held just above the surface by the Sun's magnetic field. The Earth, illustrated in the inset, is smaller than the prominence. Although very hot, prominences typically appear dark when viewed against the Sun, since they are slightly cooler than the photosphere below them. A quiescent prominence typically lasts about a month, and may erupt in a Coronal Mass Ejection (CME) expelling hot gas into the Solar System, some of which may strike the Earth and trigger auroras. Starship Asterisk* • APOD Discussion Page http://asterisk.apod.com/discuss_apod.php?date=140304 #APOD

APOD: NGC 1333 Stardust (2014 Mar 06) Image Credit & Copyright: Al Howard http://apod.nasa.gov/apod/ap140306.html Explanation: NGC 1333 is seen in visible light as a reflection nebula, dominated by bluish hues characteristic of starlight reflected by dust. A mere 1,000 light-years distant toward the heroic constellation Perseus, it lies at the edge of a large, star-forming molecular cloud. This striking close-up view spans about two full moons on the sky or just over 15 light-years at the estimated distance of NGC 1333. It shows details of the dusty region along with hints of contrasting red emission from Herbig-Haro objects, jets and shocked glowing gas emanating from recently formed stars. In fact, NGC 1333 contains hundreds of stars less than a million years old, most still hidden from optical telescopes by the pervasive stardust. The chaotic environment may be similar to one in which our own Sun formed over 4.5 billion years ago. http://www.astrophotogallery.org/m49-alhoward-protype1.html Starship Asterisk* • APOD Discussion Page http://asterisk.apod.com/discuss_apod.php?date=a140306 #APOD

APOD: In the Heart of the Rosette Nebula (2014 Mar 11) Image Credit & Copyright: Don Goldman http://apod.nasa.gov/apod/ap140311.html Explanation: In the heart of the Rosette Nebula lies a bright open cluster of stars that lights up the nebula. The stars of NGC 2244 formed from the surrounding gas only a few million years ago. The above image taken in January using multiple exposures and very specific colors of Sulfur (shaded red), Hydrogen (green), and Oxygen (blue), captures the central region in tremendous detail. A hot wind of particles streams away from the cluster stars and contributes to an already complex menagerie of gas and dust filaments while slowly evacuating the cluster center. The Rosette Nebula's center measures about 50 light-years across, lies about 4,500 light-years away, and is visible with binoculars towards the constellation of the Unicorn (Monoceros). http://www.astrodonimaging.com/ Starship Asterisk* • APOD Discussion Page http://asterisk.apod.com/discuss_apod.php?date=140311 #APOD

APOD: Messier 63: The Sunflower Galaxy (2014 Mar 13) Image Credit & Copyright: Bill Snyder (at Sierra Remote Observatories) http://apod.nasa.gov/apod/ap140313.html Explanation: A bright spiral galaxy of the northern sky, Messier 63 is about 25 million light-years distant in the loyal constellation Canes Venatici. Also cataloged as NGC 5055, the majestic island universe is nearly 100,000 light-years across. That's about the size of our own Milky Way Galaxy. Known by the popular moniker, The Sunflower Galaxy, M63 sports a bright yellowish core in this sharp, colorful galaxy portrait. Its sweeping blue spiral arms are streaked with cosmic dust lanes and dotted with pink star forming regions. A dominant member of a known galaxy group, M63 has faint, extended features that could be the result of gravitational interactions with nearby galaxies. In fact, M63 shines across the electromagnetic spectrum and is thought to have undergone bursts of intense star formation. http://billsnyderastrophotography.com/ http://www.sierra-remote.com/ Starship Asterisk* • APOD Discussion Page http://asterisk.apod.com/discuss_apod.php?date=140313 #APOD

APOD: Polar Ring Galaxy NGC 2685 (2014 Mar 14) Image Credit & Copyright: Ken Crawford http://apod.nasa.gov/apod/ap140314.html Explanation: NGC 2685 is a confirmed polar ring galaxy - a rare type of galaxy with stars, gas and dust orbiting in rings perpendicular to the plane of a flat galactic disk. The bizarre configuration could be caused by the chance capture of material from another galaxy by a disk galaxy, with the captured debris strung out in a rotating ring. Still, observed properties of NGC 2685 suggest that the rotating ring structure is remarkably old and stable. In this sharp view of the peculiar system also known as Arp 336 or the Helix galaxy, the strange, perpendicular rings are easy to trace as they pass in front of the galactic disk, along with other disturbed outer structures. NGC 2685 is about 50,000 light-years across and 40 million light-years away in the constellation Ursa Major. http://www.imagingdeepsky.com/ Starship Asterisk* • APOD Discussion Page http://asterisk.apod.com/discuss_apod.php?date=140314 #APOD

APOD: Apollo 17 VIP Site Anaglyph (2014 Mar 15) Image Credit: Gene Cernan, Apollo 17, NASA; Anaglyph by Erik van Meijgaarden http://apod.nasa.gov/apod/ap140315.html Explanation: Get out your red/blue glasses and check out this stereo scene from Taurus-Littrow valley on the Moon! The color anaglyph features a detailed 3D view of Apollo 17's Lunar Rover in the foreground -- behind it lies the Lunar Module and distant lunar hills. Because the world was going to be able to watch the Lunar Module's ascent stage liftoff via the rover's TV camera, this parking place was also known as the VIP Site. In December of 1972, Apollo 17 astronauts Eugene Cernan and Harrison Schmitt spent about 75 hours on the Moon, while colleague Ronald Evans orbited overhead. The crew returned with 110 kilograms of rock and soil samples, more than from any of the other lunar landing sites. Cernan and Schmitt are still the last to walk (or drive) on the Moon. http://www.jsc.nasa.gov/Bios/htmlbios/cernan-ea.html http://www-pao.ksc.nasa.gov/history/apollo/apollo-17/apollo-17.htm http://www.hq.nasa.gov/office/pao/History/alsj/ErikvanM.html Starship Asterisk* • APOD Discussion Page http://asterisk.apod.com/discuss_apod.php?date=140315 #APOD

APOD: Equinox on a Spinning Earth (2014 Mar 19) Image Credit: NASA, Meteosat, Robert Simmon http://apod.nasa.gov/apod/ap140319.html http://www.youtube.com/watch?v=LUW51lvIFjg Explanation: When does the line between day and night become vertical? Tomorrow. Tomorrow is an equinox on planet Earth, a time of year when day and night are most nearly equal. At an equinox, the Earth's terminator -- the dividing line between day and night -- becomes vertical and connects the north and south poles. The above time-lapse video demonstrates this by displaying an entire year on planet Earth in twelve seconds. From geosynchronous orbit, the Meteosat satellite recorded these infrared images of the Earth every day at the same local time. The video started at the September 2010 equinox with the terminator line being vertical. As the Earth revolved around the Sun, the terminator was seen to tilt in a way that provides less daily sunlight to the northern hemisphere, causing winter in the north. As the year progressed, the March 2011 equinox arrived halfway through the video, followed by the terminator tilting the other way, causing winter in the southern hemisphere -- and summer in the north. The captured year ends again with the September equinox, concluding another of billions of trips the Earth has taken -- and will take -- around the Sun. http://www.eumetsat.int/website/home/Satellites/CurrentSatellites/Meteosat/index.html http://www.nasa.gov/centers/goddard/about/people/RSimmon.html http://earthobservatory.nasa.gov/IOTD/view.php?id=52248 Starship Asterisk* • APOD Discussion Page http://asterisk.apod.com/discuss_apod.php?date=140319 #APOD

APOD: The Antennae Galaxies in Collision (2014 Mar 16) Image Credit: Hubble Legacy Archive, NASA, ESA; Processing & Copyright: Davide Coverta http://apod.nasa.gov/apod/ap140316.html Explanation: Two galaxies are squaring off in Corvus and here are the latest pictures. When two galaxies collide, the stars that compose them usually do not. That's because galaxies are mostly empty space and, however bright, stars only take up only a small amount of that space. During the slow, hundred million year collision, one galaxy can still rip the other apart gravitationally, and dust and gas common to both galaxies does collide. In this clash of the titans, dark dust pillars mark massive molecular clouds are being compressed during the galactic encounter, causing the rapid birth of millions of stars, some of which are gravitationally bound together in massive star clusters. http://hla.stsci.edu/ Starship Asterisk* • APOD Discussion Page http://asterisk.apod.com/discuss_apod.php?date=140316 #APOD

APOD: The View Near a Black Hole (2014 Mar 23) Illustration Credit: April Hobart, CXC, NASA http://apod.nasa.gov/apod/ap140323.html Explanation: In the center of a swirling whirlpool of hot gas is likely a beast that has never been seen directly: a black hole. Studies of the bright light emitted by the swirling gas frequently indicate not only that a black hole is present, but also likely attributes. The gas surrounding GRO J1655-40, for example, has been found to display an unusual flickering at a rate of 450 times a second. Given a previous mass estimate for the central object of seven times the mass of our Sun, the rate of the fast flickering can be explained by a black hole that is rotating very rapidly. What physical mechanisms actually cause the flickering -- and a slower quasi-periodic oscillation (QPO) -- in accretion disks surrounding black holes and neutron stars remains a topic of much research. http://chandra.harvard.edu/ Starship Asterisk* • APOD Discussion Page http://asterisk.apod.com/discuss_apod.php?date=140323 #APOD

Our Universe Just May Exist In A Multiverse After All, Cosmic Inflation Discovery Suggests

The first direct evidence of cosmic inflation — a period of rapid expansion that occurred a fraction of a second after the Big Bang — also supports the idea that our universe is just one of many out there, some researchers say.<p>On Monday (March 17), scientists announced new findings that mark the …

Q&A: Neil deGrasse Tyson Unveils the Cosmos

The cosmic message, according to Neil deGrasse Tyson: Take care of our world.<p>In its first airing, <i>Cosmos</i> created a new star, Cornell astronomer Carl Sagan. The seminal series opened the eyes of millions to the universe and made a science celebrity out of Sagan.<p>Now astronomer Neil deGrasse Tyson is …

Neil deGrasse Tyson

5 Sky Events of the Week: Stellar Peak-a-Boo and Leo Paws at the Moon

<b>With a change of seasons only days away, mid-March skies offer celestial sights that even the novice stargazer will find easy to enjoy.</b><p><b>Lunar rectangle.</b> After nightfall on Monday, March 10, look for the waxing gibbous moon to form a corner of a rectangle with Jupiter and the Gemini twins, Castor and …

Astronomy

Earth From Above - Live From Space Gallery

Space

Stunning Time-Lapse Video Shows Rare Views of Yosemite

Two photographers explore the park off the beaten path.<p>Explore the night sky in Yosemite National Park from the top of Echo Ridge—all in the first eight seconds of the video.<p>California-based photographers Colin Delehanty and Sheldon Neill spent more than ten months backpacking across Yosemite …

National Parks

Star Eater

Albert Einstein thought that a black hole—a collapsed star so dense that even light could not escape its thrall—was too preposterous a notion to be real. Einstein was wrong.<p>Our star, the sun, will die a quiet death. The sun’s of only average mass, starwise, and after burning through the last of its …

Physics

Catch the Space Station This Week on TV and in the Skies Above

Changing Planet<p><b>What’s it like to live and work in space? On Friday, March 14, at 8 p.m. EDT you will find out, thanks to an exciting two-hour live National Geographic TV Channel broadcast from the International Space Station (ISS) and NASA’s Johnson Space Center in Houston, Texas.</b><p>The National …

Space Exploration