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For the month of July


Summer Sky Map © Wil Tirion

July Highlights
July is a perfect time to lie back and examine the stars of the Milky Way and such summer treats as Scorpius and Sagittarius. This year's planetary lineup has broken up, and only a few of our solar system neighbors are currently easily viewable. Jupiter is still big and bright in the evening sky, setting around midnight, and Venus is beginning to appear in the morning. Those with telescopes can try to pick out Uranus, in Aquarius, or Neptune, in Capricornus, in the wee hours.

July Constellations
The jewels of summer, marking the three corners of the Summer Triangle, are the first stars visible as evening falls in July. But the skies hold plenty of other interesting sights this month as well. Ursa Major, the Great Bear, is the dominant figure in the northwestern quadrant of the sky when total darkness arrives. Most people don't recognize the full bear shape of this constellation, but nearly everyone can pick out a smaller shape, or asterism, within it: the Big Dipper. Trace a line northward from the two stars that make up the edge of the Dipper's bowl to reach Polaris, the North Star. This not-too-bright star marks the tip of the handle of the Little Dipper, which is another asterism, part of Ursa Minor, the Little Bear. Between the two bears twine the dim stars of Draco, the Dragon. This is a good month to look for Draco, as he is highest now, stretching from the northwest, above Polaris, into the northeast.

In the northeastern part of the sky is Deneb, one corner of the Summer Triangle. Deneb is the alpha (or brightest) star in the constellation Cygnus, the Swan, which is immersed in the hazy light of the Milky Way. To the left of Cygnus is Cepheus, the King, whose stars form a sort of crooked house shape. Below him is Cassiopeia, the Queen, an easily recognizable shallow W shape. The first stars of the Great Square of Pegasus are just rising above the northeastern horizon.

Sagittarius is low in the southeast. When you look toward Sagittarius you are looking in the direction of the center of our galaxy. Here the star-clouds of the Milky way are brightest, stretching up the southern sky across to the northeast, through Aquila, Cygnus, and Cassiopeia. Altair, the alpha star in Aquila, the Eagle, is in the east, and bright Vega, the alpha star in Lyra, the Lyre, is above it. They mark the other two corners of the Summer Triangle. Vega is a brilliant blue-white star, which indicates that it is young and very hot, that is the fifth-brightest star in the sky.

Arcturus, the bright orange alpha star in Bootes, the Herdsman, is in the west. Corona Borealis, the Northern Crown, forms a lovely half-circle of stars above the kite shape of Bootes. Antares, the red star marking the heart of Scorpius, the Scorpion, is due south. Like Sagittarius, it lies in front of the center of the Milky Way and has numerous star clusters and nebulas within its boundaries. It is a very interesting constellation to scan with binoculars or a telescope; pay close attention to the area around its tail. Spica, Virgo's bright alpha star, is low in the west. Between Scorpius and Virgo lie the stars of Libra, the Scales. Hercules, a rather nondescript constellation, is straight overhead. Look for the trapezoid shape called the Keystone formed by four of its stars. Along the western edge of the Keystone is M13, the brightest globular cluster (a roughly spherical group of very old stars) visible from the Northern Hemisphere. On clear nights it appears to the naked eye as a faint, slightly fuzzy star.

 

 

 

 

 

2007 eNature.com