Astronomy news for the week starting Friday, March 5, 1999.
Our Moon, our one and only natural satellite, moves through its
waning gibbous phase this week, reaching third quarter on the
morning of Wednesday, March 10 shortly after moonrise in North
America, two days after it passes its apogee, where it is farthest
from the Earth.
The great western planetary alignment -- string really -- is still
there, though starting to move out of sight. Mercury passed
greatest elongation with the Sun on March 3 and is rapidly moving
from sight into twilight glare, the little planet entering apparent
retrograde, or backward motion, toward the Sun on Tuesday the 9th,
as it prepares to pass between us and the Sun on March 19, the day
before spring begins. Jupiter, next up from the western horizon is
still bright and visible, but it too is being overtaken by evening
twilight as it moves farther and farther below brilliant Venus,
which dominates the evening sky. Unlike Jupiter and Mercury, Venus
is becoming ever more visible, climbing farther out of evening and
into the full darkness of night. Yet farther up and a bit to the
left of Venus is dimmer Saturn, the two destined to pass each other
also a day before the Sun makes it to the vernal equinox. Two
other planets, Uranus and Neptune, are on the morning side of the
Sun, six of them now bunched within a 90 degree sector of sky.
Such alignments occur all the time and have no physical effect on
us, but are certainly fascinating to watch as they show that the
planets really do move around.
That leaves little Pluto and nearby Mars, the former well above the
ecliptic plane in the constellation Ophiuchus, Mars quite by its
lonely self, having just entered the constellation Libra down and
to the left of the bright star Spica. Now rising quite brightly in
the southeast around 10:30 PM, it will meet the waning gibbous Moon
the night of Saturday, the 6th.
As the spring stars approach, look to the northeast for the Big
Dipper standing on its handle, the bowl high in the air looking for
all the world like a giant question mark, the two front bowl stars
pointing toward Polaris at the North Celestial Pole.