Earlier dark skies mean now's the time to enjoy Virgo

2014-04-24T00:00:00Z 2014-07-03T11:24:44Z Earlier dark skies mean now's the time to enjoy VirgoBy Tim Hunter Special to the Arizona Daily Star Arizona Daily Star

It is fully dark by 8:30 p.m., and now is a good time to enjoy the constellation of Virgo the Virgin.

Look toward the southeast around 9 p.m. to find Spica, the brightest star in Virgo 30 degrees above the horizon. Eleven degrees above Spica is bright red Mars which will contrast with the blue colored Spica.

To the left (north) of Mars and Spica is bright Arcturus, which has a color similar to Mars. When Spica is high in the sky, it appears bright blue to me. It is 260 light years from the sun and is visually 2,100 times more luminous than the sun, but Spica is actually much hotter than the sun. Much of its radiation is ultraviolet light rather than visible light.

Actually, Spica consists of a pair of two very close stars that orbit each other with a period of slightly more than four days.

Virgo is like an elongated, somewhat bent rectangle of stars with an extension of stars to the west. It is a large constellation, but only modestly bright. The ecliptic, the path the sun follows in the sky, goes through Virgo.

Much of Virgo’s interest to amateur and professional astronomers is the large number of important telescopic objects, mainly galaxies, spread through the constellation. The Virgo Galaxy Cluster is a cluster of up to 2,000 galaxies about 54 million light years away. These galaxies are centered in Virgo and spread over an approximate 8-degree extent.

Many of the larger, brighter members of the cluster are readily visible in amateur telescopes, making Virgo an observing favorite in the spring and summer skies. Of course, the stars in Virgo have nothing to do with the galaxies, being only nearby foreground objects sitting in front of distant galaxies.

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