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Filling the Night’s Void

The season’s brightest star shines overhead

Look for Mars high above the southwest horizon at the feet of Leo the lion, with blue-white Regulus well to the west. Saturn is high in the south, with equally bright Spica five degrees below. Mars and Saturn both shine at first magnitude, as bright as a typical star, but Mars fades noticeably over the month. Right now they are more than 30 degrees apart, but through summer they draw closer together until Mars passes the ringed planet in mid-August.
    Mercury is just now escaping the glare of the setting sun and appears a little higher and remains visible a little longer night by night. You may need binoculars to spot it amid the glare of twilight. Look for it low in the west-northwest about 30 minutes after sundown. Of the planets, only Venus and Jupiter shine brighter than Mercury, so don’t confuse it with golden Capella higher in the northwest.
    In pre-dawn skies, Jupiter rises around 5:30 in the northeast. A half-hour later, after disappearing from evening skies in its transit of the sun last week, Venus reemerges. These are the two brightest celestial objects other than the sun and moon, but Venus, at –4 magnitude, is more than twice as bright as Jupiter. Look for these two planets to the lower left of the waning crescent moon before sunrise on the 14th.
    The brightest object in the night sky is orange Arcturus, the fourth brightest star in all the heavens. Seen as the knee of Boötes the herdsman, Arcturus is a giant almost 20 times the size of our sun and four times as massive. It is older than the sun, however, and has burned through its hydrogen fuel, relying on helium for its fusion and thus is significantly cooler. By 10pm it is almost directly overhead. Finding Arcturus is as easy as finding the Big Dipper: just follow its curved handle and arc to Arcturus.