July 2006

by Deane Morrison

With Jupiter the only bright evening planet, this July is a good time to enjoy the stars. For starters, we get the best view of two famous and easily recognized constellations, Scorpius and Sagittarius, denizens of the sky's nether region.

Scorpius crawls along the horizon from east to west, its claws reaching toward Jupiter. The planet shines between the bright star Spica, the ear of grain held by Virgo, to the west and the giant red star Antares, the heart of the scorpion, to the east. Just east of Scorpius, the Teapot of Sagittarius tips as if to pour its contents on the arachnid¿s tail. Above the Teapot, the little Teaspoon hangs with its handle extending north. Sagittarius lies at the bulge of the Milky Way, and indeed the core of our galaxy is hidden behind dust clouds in this constellation.

Looking north of Jupiter, you'll see brilliant Arcturus, "follower of the bear." Arcturus gets its name from its proximity to Ursa Major, the Great Bear, the constellation that includes the Big Dipper. Whenever Arcturus is up, you can find it by following the curve of the Big Dipper's handle. This star, which anchors the kite-shaped constellation Bootes, the herdsman, is a bit of an interloper in our part of the galaxy. Instead of orbiting in the plane of the Milky Way, Arcturus is plunging down through it, following an orbit quite tilted from that of our solar system.

East of Bootes, the Corona Borealis, or Northern Crown, hangs next to the form of Hercules. That great hero kneels upside down, facing the Summer Triangle of Vega, Deneb and Altair. Closest and brightest is Vega, highlighting the parallelogram of stars in Lyra, the lyre of Orpheus. Along the southern edge of the lyre is the famous Ring Nebula, a glowing ring of gas that unfortunately requires a small telescope to see.

East of Vega, Deneb marks the tail of Cygnus, the swan. Completing the triangle is Altair, the brightest star in Aquila, the eagle. Just to the upper left of Altair, the tiny, sleek form of Delphinus, the dolphin, swims through a dark sea.

As usual in July, the moon sweeps close to the southern horizon, coming close to Jupiter on the 5th, Antares on the 7th, and Spica on the 31st. A very old moon comes up near Venus in the morning sky on the 22nd and 23rd. July¿s full moon, called the hay moon or thunder moon, arrives on the 10th. The moon rises that evening at 9:22 p.m. CDT¿only 40 minutes before the moment of fullness¿against a background of lingering twilight. Therefore, if clouds don¿t interfere, the rising moon will appear very round and softly lit.

Earth reaches aphelion, its farthest distance from the sun, at 6:11 p.m. CDT the 3rd. On that day Earth swings out to 94.5 million miles from the sun, about 3.4 percent farther than at its closest approach (perihelion) in January.