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Glorious Sunrise

Photo of the Week. Glorious Sunrise.

Astronomy news for the week starting Friday, December 25, 2009.

Wishes for a fine holiday season to all.

The Moon cooperates in the celebrations by taking the last week of the year to go through its entire waxing gibbous phase, beginning with first quarter on Thursday, December 24, Christmas Eve, and culminating on Thursday, December 31, New Year's Eve, with its full phase.

A variety of lunar events and effects enhance the affair. First, this full Moon -- the Cold Moon, the Long Night Moon -- is the second one for the month of December, the first having taken place the night of December 1. Since the first one already has a traditional name, this one is by more-or-less recent folk tradition called a "blue moon." Its color, however, will be the usual silver white (or reddish if rising).

Second, the Moon highlights the end of the year by being partially eclipsed by the shadow of the Earth. Unfortunately, full Moon takes place during mid-day in North America, with the Moon quite out of sight, so it's a European, African, and Asian affair. But don't feel sorry for ourselves, as it is not much of an eclipse, the south pole of the Moon just barely ticking the dark terrestrial umbra. Those on the other side of the world won't see much either. Then, with the Sun still very close to the Winter Solstice in Sagittarius, the full Moon -- opposite the Sun -- will be just to the east of the Summer Solstice in classical Gemini (never mind that the Earth's precessional wobble has taken the Solstice across the "official" border into Taurus). This full Moon will therefore be the highest of the year, at least as seen from the mid-northern hemisphere, as it will more or less replicate the behavior of the Sun on the first day of summer (perhaps making us feel warmer).

Enough of the Moon; on to the planets! While slipping away to the west, Jupiter remains nicely visible in early evening, dropping to the horizon to set around 8:30 PM. Earlier, you might catch a glimpse of Mercury in southwestern twilight. Mars, still rising just before Jupiter disappears, continues to brighten in western Leo, the two planets nearly opposite one another. Saturn then passes a bit of a milestone by rising around midnight in western Virgo, as it becomes an evening object. Our planetary year then finally ends with Pluto going through conjunction with the Sun on Christmas Eve, making it doubly invisible.

Early evening is about your last chance to see Fomalhaut to the southeast of Jupiter. But to the northeast of the giant planet, the Andromeda gang still hangs around. In particular it's a wonderful season for the star-streams of Perseus, who rides high, nearly overhead, in mid-to-late evening.
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