Skylights featured three times on Earth Science
Picture of the Day: 1
, 2
, 3
, 4
.
Photo of the Week.. The Sun sets slowly over the
a Mediterranean island as a cloud drifts to the left. After
sunset, a faint sunpillar appears.
Astronomy news for the week starting Friday, January 16, 2004.
Skylights now resumes its regular weekly schedule.
This is the week of the crescent Moon. It starts in its waning crescent phase, when it is
seen in the east in the dawn sky, goes through new on Wednesday the
21st, and then starts to wax as
a difficult-to-find sliver in the southwest in bright evening
twilight the night of Thursday the 22nd. Two days before new, the
Moon goes through perigee, where it is closest to the Earth. Be
sure to admire the "Earthlight" that lights up the Moon's nighttime
side.
Use the Moon to find Mercury. On Saturday the 17th, the
little planet, only 39 percent our distance from the Sun, goes through its greatest western elongation, where it
is at its maximum angle (a mere 24 degrees) from the Sun and at its
best visibility. The morning of Sunday the 18th finds the thin
crescent Moon just to the left of the star Antares in Scorpius (which just recently cleared the Sun).
Mercury will be well down and to the left of the lunar crescent.
The following morning, Monday the 19th, is even better, as Mercury
will be directly to the left of the crescent. As always, viewing
of Mercury requires a clear, unobstructed horizon.
Venus, on the other hand, requires no guide. Just look in
evening twilight in the southwest for the brightest thing you can
see. Getting higher each evening, Venus (72 percent our distance
from the Sun) does not now set until 8 PM, well after the end of
twilight. At the same time, find Saturn
nicely up in the northeast in southwestern Gemini, the ringed planet seen high to the south by 11
PM. Then about an hour after Venus sets,
Jupiter rises south of the classical figure of Leo. While not rivalling Venus, the
giant planet is still amazingly bright. Between Venus and Saturn
lies faithful Mars, seen to
the west of south at the end of twilight. Entirely in the evening
sky now, the
red planet sets just before midnight.
As Cassiopeia, the Queen, swings
around the northern pole, she is followed closely by Perseus, the Hero of the Andromeda tale. By 8 PM or so,
the streams of stars that make Perseus hang high in the northern
sky, led by Mirfak, the Alpha
star, which gives the name to a bold cluster, the Alpha Persei Cluster. South of
Mirfak lies one of the most famous stars of the whole sky, Algol, the Demon Star, an eclipsing binary that
"winks" at you, dropping from second to third magnitude and back
every 2.87 days. In a dark sky, the Milky Way
can be seen streaming out of Cassiopeia through Perseus and then,
fading, through southern Auriga,
falling thereafter to the east of great Orion.
