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Earthsky Tonight—May 18, Moon near Mars, Castor, Pollux
Posted By Gary Wamsley On May 18, 2010 @ 6:09 am In Earth & Sky | Comments Disabled
Courtesy of EarthSky
A Clear Voice for Science
 At nightfall, the waxing crescent moon  lines up with Castor and Pollux, the two brightest stars in the constellation Gemini the Twins.
People often refer to these stars as ‘The Twins’ but they aren’t really twins at all. At a distance of about 34 light-years , Pollux wins acclaim as the closest giant star to our solar system. It’s one of the very few giant stars in our galaxy known to harbor a planet.
Castor is farther away, at 52 light-years. It looks like a single star to the eye, but it’s actually six stars in one, all revolving around one another in an intricate dance.
With binoculars, you may discern Castor and Pollux’s contrasting colors . Pollux looks orange whereas Castor appears white. An orange star has a relatively low surface temperature, indicating that Pollux  is in the autumn of its years. On the other hand, a more youthful star – like Castor  – displays a white color, a sure sign of this star’s higher surface temperature.
Last but hardly least, look for the ruddy planet Mars to the upper left of the moon. The moon will haved move much closer to Mars by this time tomorrow  night.
Written by Deborah Byrd
CHANDRA Photo Album 
StarDate Online 
Sky and Telescope 
National Geographic 
Space Com 
Amazing Space 
Scope City 
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URL to article: http://www.berthoudrecorder.com/2010/05/18/earthsky-tonight%e2%80%94may-18-moon-near-mars-castor-pollux/
URLs in this post:
 www.EarthSky.org: http://www.EarthSky.org
 Image: http://www.berthoudrecorder.com/wp-content/uploads/2010/05/May-19_phases-waxing-crecent.jpg
 Image: http://www.berthoudrecorder.com/wp-content/uploads/2010/05/10may18_4301.jpg
 waxing crescent moon: http://earthsky.org/tonightpost/moon-phases/waxing-crescent
 light-years: http://earthsky.org/tonightpost/astronomy-essentials/how-far-is-a-light-year
 colors: http://earthsky.org/faqpost/space/star-colors
 Pollux: http://earthsky.org/tonightpost/brightest-stars/pollux-not-castor-is-geminis-brightest-star
 Castor: http://earthsky.org/tonightpost/brightest-stars/best-castor-brightest-second-magnitude-star
 tomorrow: http://earthsky.org/es-tonight/moon-and-mars-close-together
 Astronomy Picture of the Day from NASA/JPL: http://antwrp.gsfc.nasa.gov/apod/
 CHANDRA Photo Album: http://chandra.harvard.edu/photo/
 U.S. Naval Observator Astronomical Information cente: http://www.usno.navy.mil/USNO/astronomical-applications/astronomical-information-center/astronomical-information-center
 StarDate Online: http://stardate.org/
 Sky and Telescope: http://www.skyandtelescope.com/observing/ataglance/
 National Geographic: http://news.nationalgeographic.com/news/
 Space Com: http://www.space.com/nightsky/
 Amazing Space: http://amazing-space.stsci.edu/tonights_sky/
 The York County Astronomical Society: http://www.ycas.org/tonights_sky.htm
 Scope City: http://www.scopecity.net/
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