Skylights featured three times on Earth Science
Picture of the Day: 1
, 2
, 3
.
Photo of the Week.. Shafts of sunlight poke through
holes in a sheet of clouds. Really parallel, perspective makes
them look as if they are radiating away from the hidden Sun.
Astronomy news for the week starting Friday, February 21, 2003.
The Moon passes through its last
quarter this week on Sunday the 23rd, around the time it sets.
Before dawn it will be found near the head of Scorpius and northwest of the great star Antares. The Moon will thereafter
wane through its crescent
phase, best visible in the early morning hours, as it
approaches its new phase early next month.
As it travels along its zodiacal path, the Moon will make a fine
pass south of Mars the night of
Monday the 24th, and then be just to the southeast of the planet
after they both rise the morning of Tuesday the 25th. Be sure to
compare brightening Mars with Antares, seen to the west of the
planet. Not only are they nearly the same color, but they are now
close to the same brightness. As the Earth catches up with the red
planet, it will vastly exceed the brightness of the star. While
focussing in on this part of the sky, take particular note of the
middle star of Scorpius's head, Dschubba (Delta Scorpii), which has
undergone something of an outburst and has brightened over the past
couple years almost to first magnitude, somewhat changing the
appearance of the constellation.
The next "stop" for the Moon (it of course does not stop, or would
fall to Earth) is Venus. The
morning of Thursday the 27th, the slimming crescent will pass five
degrees to the south of the brilliantly glowing planet.
Except for the Moon, Venus glows far brighter
than anything else in the sky. At the end of the week, on Friday
the 28th, the Moon will pass south of Neptune, the
"event" as such not terribly visible. That the Moon is passing
well to the south of all these planets reveals the tilt of its
orbit, which it taking the Moon south of the ecliptic (the path of
the Sun) and then well south of the Sun itself, thereby avoiding a
solar
eclipse. Only when the Moon is crossing the ecliptic at new
phase will such an event occur (and only when crossing the ecliptic
at full phase do we get a lunar
eclipse).
As March approaches, the winter constellations are in full form in
the very early evening. High to the south is glorious Orion, and higher and up and to the
right is Taurus, the celestial
bull, which contains not just the two clusters of the Hyades (which makes the Bull's
head, Aldebaran his eye) and the Pleiades (the Seven Sisters), but also (temporarily in
eastern Taurus) Saturn, the
planet undergoing an orbital transition, as it ceases retrograde motion on Saturday the 22nd and resumes direct
easterly motion. Then look to the east of Saturn to see rising
that harbinger of spring, Leo (the
Lion), which precedes Cancer the
Crab, which in turn holds very bright Jupiter, the
giant planet now well up in the east at sunset.
