Skylights featured three times on Earth Science
Picture of the Day: 1
, 2
, 3
, 4
.
Photo of the Week.. Memories of early autumn lie
against the blue of the distant sky.
Astronomy news for the week starting Friday, December 3, 2004.
The week begins with the Moon just shy of its third
quarter, allowing the skies to darken once again. After the
passage of the phase on the night of Saturday, December 4, rather
well before Moonrise in North America, the Moon wanes in its crescent, becoming ever thinner in
the early pre-dawn sky.
Watch the Moon as it passes by stars and planets, marking them out
one by one. The morning of Wednesday the 8th, our companion will
appear just down and to the left of first magnitude Spica in Virgo. Look for Jupiter
higher in the sky in western
Virgo to the other side of Spica. The next morning, on
Thursday the 9th, the Moon will help form a line that leans down
and to the left, the Moon on top, Mars in
the middle, and Venus
below. To the left of the Moon will be much fainter Zubenelgenubi in Libra. By the morning of Friday the
10th, the positions will be reversed, the Moon now below Venus as
they all climb out of eastern dawn. Of the three planets, Venus
(at minus fourth magnitude) is by far the brightest, minus-second
magnitude Jupiter next, Mars (second magnitude) by far last.
Earlier in the week, the morning of Sunday the 5th, Venus and Mars
come into conjunction, creamy-white Venus 1.3 degrees to the north
of the more distant red planet.
Jupiter, well to the west of the Venus-Mars duo and now rising
around 2 AM, slowly moves toward the evening sky. The evening
itself is now graced by Saturn in Gemini,
which clears the northeastern horizon around 7:30 PM. In contrast,
innermost Mercury
is quite invisible as it passes inferior conjunction with the
Sun the morning
of Friday the 10th as it passes from evening to morning.
'Tis the Earth
in the news, though. While the shortest day in the northern
hemisphere falls at the passage of the Sun over the Winter Solstice (on December 21), the
earliest sunset takes place on Tuesday the 7th, the offset the
result of the eccentricity of the Earth's orbit and the 23.5 degree tilt of the
terrestrial axis, which together put the Sun rather well ahead of
its average, smooth-motion position. While the morning Sun will
keep rising later until well into winter, the evening Sun will
begin to set later, giving us more light on the evening drive home.
High above in northern mid-evenings find Cassiopeia, the Queen of the ancient legend of Andromeda and Perseus. To the west is Cassiopeia's
husband, King Cepheus, which is
more difficult to find as it is not marked out by a slew of bright
stars. Beneath the two figures find Polaris, the North Star, about which
they nightly whirl. Directly
opposite, and below the pole, lies the Big Dipper of Ursa
Major, whose bowl is now tipped to "hold water," all of the
figure circumpolar and visible from the far northern US and most of
Canada.
