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Earthsky Tonight — April1, 2010 Follow the arc to Arcturus
Posted By Gary Wamsley On March 31, 2010 @ 9:21 pm In Earth & Sky | Comments Disabled
Courtesy of EarthSky
A Clear Voice for Science
Now is the perfect time to look outside in the evening and learn a phrase useful to skywatchers. Scouts learn it. Grandparents teach it to kids. It was one of the first sky tools I learned to use in astronomy.
The phrase is: follow the arc to Arcturus.
First locate the Big Dipper asterism in the northeastern sky in mid-evening, maybe around 9 p.m. Can’t find the Big Dipper? Look ahead to our chart for April 6 .
Once you can see the Big Dipper, notice that it has two parts: a bowl and a handle. Then – with your mind’s eye – draw an imaginary line following the curve in the Dipper’s handle until you come to a bright orange star. This star is Arcturus in the constellation Bootes, known in sky lore as the Bear Guard.
Arcturus  is a giant star with an estimated distance of 37 light-years. It is special because it’s not moving with the general stream of stars, in the flat disk of the Milky Way galaxy. Instead, Arcturus is cutting perpendicularly through the galaxy’s disk at a tremendous rate of speed . . . some 150 kilometers per second. Millions of years from now this star will be lost from the view of any future inhabitants of Earth, or at least those who are earthbound and looking with the eye alone.
However, for now Arcturus is one of the easiest stars to find, using the Big Dipper as a guide. Try it, on a lovely spring evening soon.
Written by EarthSky
Space Com 
Amazing Space 
Scope City 
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URLs in this post:
 www.EarthSky.org: http://www.EarthSky.org
 Image: http://www.berthoudrecorder.com/wp-content/uploads/2010/03/10apr01_430.jpg
 April 6: http://earthsky.org/es-tonight/use-big-dipper-to-find-polaris-and-little-dipper
 Arcturus: http://earthsky.org/tonightpost/brightest-stars/bright-orange-arcturus-use-the-big-dipper-to-find-it
 Give me five minutes, I’ll give you Saturn: http://earthsky.org/tonightpost/astronomy-esentials/give-me-five-minutes-ill-give-you-saturn
 Astronomy Picture of the Day from NASA/JPL: http://antwrp.gsfc.nasa.gov/apod/
 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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