Christen Cook

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APOD: ALMA Milky Way (2014 Jul 24) Image Credit & Copyright: Yuri Beletsky (Las Campanas Observatory, Carnegie Institution) http://apod.nasa.gov/apod/ap140724.html Explanation: This alluring all-skyscape was taken 5,100 meters above sea level, from the Chajnantor Plateau in the Chilean Andes. Viewed through the site's rarefied atmosphere at about 50% sea level pressure, the gorgeous Milky Way stretches through the scene. Its cosmic rifts of dust, stars, and nebulae are joined by Venus, a brilliant morning star immersed in a strong band of predawn Zodiacal light. Still not completely dark even at this high altitude, the night sky's greenish cast is due to airglow emission from oxygen atoms. Around the horizon the dish antenna units of the Atacama Large Millimeter/submillimeter Array, ALMA, explore the universe at wavelengths over 1,000 times longer than visible light. http://www.lco.cl/ http://carnegiescience.edu/ Starship Asterisk* • APOD Discussion Page http://asterisk.apod.com/discuss_apod.php?date=140724 #APOD

APOD: NGC 7023: The Iris Nebula (2014 Aug 02) Image Credit & Copyright: Jimmy Walker http://apod.nasa.gov/apod/ap140802.html Explanation: These clouds of interstellar dust and gas have blossomed 1,300 light-years away in the fertile star fields of the constellation Cepheus. Sometimes called the Iris Nebula, NGC 7023 is not the only nebula in the sky to evoke the imagery of flowers, though. Still, this deep telescopic view shows off the Iris Nebula's range of colors and symmetries in impressive detail. Within the Iris, dusty nebular material surrounds a hot, young star. The dominant color of the brighter reflection nebula is blue, characteristic of dust grains reflecting starlight. Central filaments of the dusty clouds glow with a faint reddish photoluminesence as some dust grains effectively convert the star's invisible ultraviolet radiation to visible red light. Infrared observations indicate that this nebula may contain complex carbon molecules known as PAHs. The pretty blue petals of the Iris Nebula span about six light-years. http://jwalk.smugmug.com/ Starship Asterisk* • APOD Discussion Page http://asterisk.apod.com/discuss_apod.php?date=140802 #APOD

APOD: Milky Way over Yellowstone (2014 Aug 27) Image Credit & Copyright: Dave Lane http://apod.nasa.gov/apod/ap140827.html Explanation: The Milky Way was not created by an evaporating lake. The colorful pool of water, about 10 meters across, is known as Silex Spring and is located in Yellowstone National Park in Wyoming, USA. Illuminated artificially, the colors are caused by layers of bacteria that grow in the hot spring. Steam rises off the spring, heated by a magma chamber deep underneath known as the Yellowstone hotspot. Unrelated and far in the distance, the central band of our Milky Way Galaxy arches high overhead, a band lit by billions of stars. The above picture is a 16-image panorama taken late last month. If the Yellowstone hotspot causes another supervolcanic eruption as it did 640,000 years ago, a large part of North America would be affected. Starship Asterisk* • APOD Discussion Page http://asterisk.apod.com/discuss_apod.php?date=140827 #APOD

APOD: The Starry Sky under Hollow Hill (2014 Aug 30) Image Credit & Copyright: Phill Round http://apod.nasa.gov/apod/ap140830.html Explanation: Look up in New Zealand's Hollow Hill Cave and you might think you see a familiar starry sky. And that's exactly what Arachnocampa luminosa are counting on. Captured in this long exposure, the New Zealand glowworms scattered across the cave ceiling give it the inviting and open appearance of a clear, dark night sky filled with stars. Unsuspecting insects fooled into flying too far upwards get trapped in sticky snares the glowworms create and hang down to catch food. Of course professional astronomers wouldn't be so easily fooled, although that does look a lot like the Coalsack Nebula and Southern Cross at the upper left ... http://apod.nasa.gov/lib/about_apod.html#srapply photofilatihugdotcodotnz Starship Asterisk* • APOD Discussion Page http://asterisk.apod.com/discuss_apod.php?date=140830 #APOD

APOD: Airglow Ripples over Tibet (2014 Sep 01) Image Credit & Copyright: Jeff Dai http://apod.nasa.gov/apod/ap140901.html Explanation: Why would the sky look like a giant target? Airglow. Following a giant thunderstorm over Bangladesh in late April, giant circular ripples of glowing air appeared over Tibet, China, as pictured above. The unusual pattern is created by atmospheric gravity waves, waves of alternating air pressure that can grow with height as the air thins, in this case about 90 kilometers up. Unlike auroras powered by collisions with energetic charged particles and seen at high latitudes, airglow is due to chemiluminescence, the production of light in a chemical reaction. More typically seen near the horizon, airglow keeps the night sky from ever being completely dark. http://apod.nasa.gov/lib/about_apod.html#srapply http://www.flickr.com/photos/jeffdai/ Starship Asterisk* • APOD Discussion Page http://asterisk.apod.com/discuss_apod.php?date=140901 #APOD