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06/11/2012 – Ephemeris – The bright star Arcturus

June 11, 2012 Comments off

Ephemeris for Monday, June 11th.  Today the sun will be up for 15 hours and 30 minutes, setting at 9:27.   The moon, at last quarter today, will rise at 1:55 tomorrow morning.  Tomorrow the sun will rise at 5:56.

The bright star Arcturus appears high in the south at 10:30 in the evening.  It’s at the base of a kite shaped constellation of Boötes the herdsman or bear chaser.  Arcturus is remarkable for several reasons.  It is only 10 percent more massive than the sun but is 110 times brighter and is orange in color.  That’s because Arcturus has entered its red giant stage of life after depleting hydrogen in its core as its fuel source.  Arcturus is much older than the sun to have evolved so far, being only a little more massive than the sun.  Also Arcturus may be new to our galaxy, Its rapid motion of 76 miles per second with respect to the sun, along with 51 other stars known may have come from a small galaxy that collided with the Milky Way.

Times are for the Traverse City/Interlochen area of Michigan.  They may be different for your location.

Addendum

Bootes and the Big Dipper

Arcturus, Boötes and the Big Dipper

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