A Big Moon by Any Name
As twilight settles to darkness, look to the southwest for ruddy Mars beside the ice-blue of Spica until they set around midnight. Mars is the brighter of the two. They will be their closest Sunday, with less than 1.5 degrees separating them. After that, Mars keeps on trucking, setting course for a conjunction with Saturn on August 4.
Saturn is high in the south at twilight and remains an easy target until setting in the west around 1am. The ringed planet has been inching eastward night after night in a retrograde motion, but that is near the end. Next week on the 21st Saturn’s apparent motion stops, and for several weeks you’ll find it poised above the constellation Libra, just a couple degrees above Zubenelgenubi, the fulcrum of the celestial scales. A few degrees higher than Saturn is Zubeneschamali, a second-magnitude star that appears to some to glow a greenish hue — the only star with that distinction.
If you’re up an hour or so before the dawn, you should have no trouble spotting Venus ablaze above the east-northeast horizon at magnitude –3.8. Only the sun and moon appear brighter.
You’ll have a harder time finding Mercury, midway between Venus and the horizon. The innermost planet reaches greatest elongation Saturday — its point farthest from the sun from our vantage. But you’ll still have to hunt for Mercury, which once found appears surprisingly bright. Mercury and Venus come their closest on the 17th, within just six degrees of one another .
The moon appears full both Friday and Saturday, blanketing the night sky with its glow from sunset to sunrise. Commonly called the Thunder Moon, the Buck Moon and the Hay Moon, July’s full moon this year is also a Super Moon. This time of year, the moon travels through our skies in its lowest arc. So close to the horizon, the moon appears larger than usual in contrast to earth-bound objects seen in the same field of view. While this phenomenon is an optical illusion, the moon right now is closer to earth. On average the moon is roughly 238,000 miles away; when the moon comes within 224,851 miles of earth, as it is now, it is dubbed a Super Moon. The next two full moons will also be Super Moons, with the one in August only 221,765 miles from earth.