Astronomy news for the week starting Friday, December 3, 2010.
This is the dark-sky week of the new
Moon, the phase passed early, on Sunday, December 5, after
which it spends its time waxing in the crescent phase. With luck you might see the ultra-thin crescent in evening twilight the
night of Monday the 6th, the view improving on subsequent nights.
As it goes along its zodiacal
path, the Moon invisibly passes Mercury (which
is not presenting much of an apparition) on Tuesday the 7th.
Though formal winter and the shortest day of the year are yet a ways
off, take heart, as because of the eccentricity of the Earth's
orbit and the tilt of its axis, the earliest sunset is coming up on
Tuesday the 7th, after which it will begin to get lighter in the
evening.
The evening and morning hours are dominated by the two brightest of
planets, Jupiter and
Venus. Jupiter, now in direct easterly motion near the Aquarius-Pisces border, transits the meridian to the south about 6:30 PM, less
than half an hour past the end of evening twilight, setting half an hour
after midnight. But an hour and a half later, up comes Saturn, still well to
the west of Virgo's Spica.
The real show, however, begins just after 3:30 AM, when Venus lofts
itself up above the still-dark eastern horizon. Positively
glowing, the amazing planet remains easily visible well into bright
twilight. Hitting a morning milestone, it reaches greatest
brilliancy the morning of Saturday the 4th, its subsequent fading
not for some time noticeable to the eye. Seen as a crescent through
the telescope, Venus is so bright that it is visible in full
daylight and in a dark sky will cast eerie shadows on the ground.
Back in the evening, Uranus, still just over
a couple degrees to the northeast of Jupiter, ceases
retrograde motion on Monday the 6th, when it begins its normal
easterly movement against the stars. Faster moving Jupiter will
catch up with next January 2, when the two will be a mere 0.6
degree apart, about the angular diameter of the full Moon.
Jupiter provides a good guide to one of the fainter constellations of the Zodiac. Look
just to the north of it to find the ragged circle of stars that
makes the "Circlet" of Pisces, the celestial Fishes. The
rest of the figure sprawls in a long line to the east until it
meets up with another rough circle that makes the head of Cetus, the Whale or Sea Monster,
after which it turns to the north. Just to the right of the
Circlet, find the Y-shaped "Water
Jar" of Aquarius.
