Look Up--Again!

More than fireworks will light July's skies for nights to come

By Bob Berman|Thursday, July 01, 1999
RELATED TAGS: SOLAR SYSTEM
The millions of patriotic Americans who willingly put up with traffic jams, mosquitoes, and neck cramps to gaze upward at man-made pyrotechnics each Fourth of July tend to forget that other nights of the month also offer their own wealth of spectacular celestial objects.

A perfect example: Venus, the dazzling evening star, which dramatically pops out of the western sky as twilight fades at around 9 P.M. The planet's sudden appearance will fool many into believing they're seeing an airplane or even a UFO. Our nearest planetary neighbor--shining at a magnitude -5, which is 100 times brighter than any other star in the sky--hasn't been this brilliant in nearly two years.

On July 15, Venus, along with our own crescent moon and the blue star Regulus, will bunch tightly together for a rare conjunction. A close meeting of Venus and the moon, the night's two most brilliant objects, is always a treat. The addition of Regulus, the brightest star in the constellation Leo, will produce an unforgettable rendezvous.

Like good fireworks, Venus blazes most intensely just before it disappears. Early in the month, the evening star hovers high enough above the horizon to be strikingly obvious in the western twilight. By next month, however, the planet will have dropped below the skyline. We won't enjoy such a dazzling evening star again for two years.

July's long dusk also features a lovely Mars, located about halfway up the southern sky. For a little bit of fun, casually say "that's Mars," and watch for your eavesdropping neighbors to whirl around to see where you're pointing.

They'll have no trouble finding the Red Planet. Mars was at its best a few months back, but it's still impressive now. On the Fourth of July, its official magnitude will be -.4, placing it second in brightness only to Venus. To further improve the view, note that Mars sits just to the left of Spica, Virgo's sizzling blue ultrahot star. (If you have a gifted imagination, that constellation resembles a virgin--but it really looks more like the letter Y.) The vivid color contrast between red Mars and blue Spica proves that the starry sky is not an unvarying white. But look now, not later, for Mars, because the planet rapidly dims in the days ahead as Earth speeds away from it at 66,000 miles per hour.

Our two closest planetary neighbors signal other worthwhile sights this month. For a challenge, serious amateurs can hunt for variable stars, like the on-and-off sky winker Beta Lyrae. Located almost straight overhead, near bright Vega, Beta Lyrae looks like one star. But that single point of light is really a pair of strange, football-shaped stars that regularly eclipse each other. Every 13 days, one completely hides the other. This month, the eclipse will happen on the eleventh, when light from that pinpoint will be half as bright.

Or you could look to the northeast, where the famous Algol rises. Wary Arabian sky watchers called Algol the ghoul, or demon, because the star spookily loses most of its light like clockwork every two days, 20 hours, and 49 minutes, as an unseen orbital companion slides in front of it.

Those are only a few examples of a July filled with heavenly wonders that compete well with bursting bombs and streaking flares. Look for them as you wait for the fireworks to begin. And remember, they'll be there long after the fat lady sings "The Star-Spangled Banner."
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