Astronomy news for the week starting Friday, June 25, 1999.

The Moon heads toward its full phase this week, reaching it on Monday, the 28th, shortly before moonrise in North America, making the full Moon rise just a bit after sunset. Three days before, on Friday the 25th, the Moon goes through its apogee, where it is farthest from the Earth, a distance 5.5% greater than average.

Venus still dominates the evening sky to the west, while Mars, to the south, comes in at close second place while it slowly pulls to the east of the bright star Spica. Third and last in line among evening planets is Mercury, which is making a fine appearance in the northwest shortly after sundown, setting an hour and a half after the Sun. On Monday the 28th, the little planet, the smallest in the Solar System save Pluto, will reach greatest eastern elongation, when it is a nice 26 degrees to the east of the Sun. Though Mercury is very bright, at elongation comparable to Vega and Arcturus (the latter high to the south as the sky grows dark), it is hard to see against the twilight sky. A quick scan with binoculars, however, will pick it up easily. If you wish to see the other two planets, Jupiter and Saturn, you will need to stay up until the morning hours past 2 AM to watch them rise in the east, Jupiter first, the bright planet now gliding in direct motion to the east against the stars of Pisces.

Since the near-full Moon will wash out all but the brighter stars, it is a good time to admire the brightest the sky has to offer. Vega, now climbing the northeastern sky in early evening is of magnitude zero and just slightly less bright than Arcturus, the two providing a fine color contrast, Vega white and Arcturus a soft orange (different eyes seeing distinctly different shades). Compare Arcturus with Antares in Scorpius low to the south around 11 PM, the supergiant Antares the cooler, and thus the redder, of the two, its color enhanced by atmospheric absorption due to its low altitude above the horizon. To the east again, Vega is the northwestern apex of the rising Summer Triangle, which also contains first magnitude white Deneb in Cygnus, east of Vega, and also-white Altair in Aquila, which anchors the Triangle to the south.
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