Sunday, June 27, 2010

July skywatch: Hercules floats high, 5 planets align

by John Stanley The Arizona Republic Jun. 25, 2010 06:36 PM

Summer nights may be short, but they're packed with astronomical treats.

One of the best is Hercules, a constellation recognized throughout the ancient Mediterranean world.

Hercules is known for his 12 labors, which ranged from slaying the multiheaded Hydra to obtaining the belt of Hippolyta, the queen of the Amazons, to descending into the underworld to capture Cerberus, the watchdog of Hades.

Associated legends claim that Hercules sailed with the Argonauts, celebrated the first Olympic Games and freed Prometheus from his chains.

Despite Hercules' stature in the ancient world, his constellation isn't terribly prominent. It is, however, easy to find in July.

Face east about an hour after sunset. The bright white star in the northeast is Vega; the bright, slightly orange star nearly overhead is Arcturus.

If you're not sure, first find the Big Dipper to the north, then follow the curve of its handle over to Arcturus. (Remember: You arc to Arcturus.)

Vega and Arcturus are the two brightest stars in the northern hemisphere of the sky. Hercules is midway between them.

If you're observing from a light-polluted site, you may not see much of anything without binoculars.

The main part of Hercules is composed of six stars arranged in what is often described as a butterfly shape, although it looks more like a slightly lopsided bowtie.

One of the finest globular clusters visible to Earth-bound observers floats within Hercules. If you're observing from a truly dark location, you might catch a glimpse of M13 with your naked eye. Most observers, though, will need binoculars to pick out what appears to be a small, ghostly patch of light. And it takes a telescope to show the cluster in all its glory - a roughly spherical association of hundreds of thousands of stars.

M13 is nearly 150 light-years in diameter and about 25,000 light-years away.

Moon and planets

In mid-July, four of the five naked-eye planets will be lined up like a string of celestial pearls in the west after sunset.

Venus will be by far the most obvious, shining brilliantly in the west-northwest. Look for faint Mercury well below and to the right of Venus; Mars, distinctly orange, will be above and to the left of Venus; Saturn, brighter than Mars but not nearly so bright as Venus, will be well above and to Mars' left.

The crescent moon drifts through the region from July 13-16 and serves as a guide to the planets.

Mercury will be to the right of the low crescent moon about 30 to 45 minutes after sunset July 13. Venus will be above and to the right of the higher and slightly fatter crescent on the 14th, Mars will be above and to the right of the moon on the 15th, and Saturn will be above and well to the right of the moon on the 16th.

Space anniversary

Thirty-five years ago, the U.S. and Soviet Union, fierce competitors in the space race of the 1960s, flew their first joint mission: the Apollo-Soyuz Test Project.

Thomas Stafford, veteran of Apollo 10 and two Gemini flights, commanded the U.S. team, which lifted into orbit July 15, 1975. His crew consisted of rookie astronauts Vance Brand and Donald "Deke" Slayton, one of the original Mercury Seven astronauts, who had been grounded since 1961 because of a heart murmur; this was his only spaceflight.

The Soviet crew consisted of Alexei Leonov, the first person to walk in space, and Valeri Kubasov, who was making his second spaceflight.

More on this topic
Dorrance Planetarium

What: A half-dozen shows ranging from astronomy in ancient Egypt to black holes to tips for spotting objects in Arizona's night sky.

When: Starting times range from 11 a.m. to 4:30 p.m. daily.

Where: Arizona Science Center, 600 E. Washington St., Phoenix.

Admission: $7-$8 in addition to science center admission of $10-$12.

Details: 602-716-2000,

July skywatch: Hercules floats high, 5 planets align

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