Skylights featured three times on Earth Science
Picture of the Day: 1
, 2
, 3
, 4
.
Photo of the Week.. A towering sky backlights a
quiet Earth.
Astronomy news for the week starting Friday, March 25, 2005.
Skylights now resumes its usual weekly schedule.
The week is bracketed by two
phases of the moment," beginning with full Moon on Friday,
March 25 (during the day, causing the Moon to rise a bit after
sundown that night) and ending with the third quarter on Friday,
April 1 (no fooling!). In between, the Moon wanes through its gibbous phase, as
we watch the lunar sunset line creep to the left across the lunar
disk. A telescopic view of the "terminator" (the sunset line that
separates the daylight from the nighttime side) will show mountain
peaks and crater walls catching their last rays of
sunlight. The night of Friday the 25th, watch the Moon rise
above (to the west of) giant
Jupiter. Porrima, Gamma
Virginis, will be just to the north (at moonrise to the left) of
the bright lunar disk. Can you see it? The following night, the
barely-waning gibbous Moon will rise AFTER Jupiter as it prepares to
pass to the north of Spica, which
should be easily visible.
Given that Jupiter is just to the east of the full Moon, it must be
closing in on opposition with the Sun, and indeed opposition will
be reached on Sunday, April 3. Jupiter therefore now rises just
after sunset and crosses the meridian to the south just half an
hour after midnight. The next planet out, Saturn
(in Gemini), is now crossing the
meridian high to the south in mid-twilight, setting about 2:30 AM,
a bit over half an hour before Mars rises.
Tracking swiftly to the east, Mars has moved into Capricornus, and is nicely visible in
the southeast as dawn begins to light the sky.
The two inner planets join in nearly simultaneous conjunctions with
the Sun, but on opposite sides of it. On Tuesday the 29th, Mercury goes
through inferior conjunction, when it is between us and the Sun
(passing to the north of the solar disk), while just a day later,
Venus goes through
superior conjunction (on the other side of the Sun). Mercury
thereby makes a transition from the evening to the morning sky,
while Venus moves from morning to evening. Climbing only slowly
out of evening twilight, Venus will become visible in the west in
late spring.
Though spring is now upon us, winter's Orion still shines majestically to the southwest as the
sky darkens, Orion's larger hunting dog (Canis Major) with Sirius south and to the left, the
smaller dog (Canis Minor) with Procyon to the northeast of Sirius.
As the weather warms, the Winter
Triangle of Betelgeuse (in
Orion), Sirius, and Procyon will be replaced by the summer version of Vega, Deneb, and Altair.
