Astronomy news for the week starting Friday, September 1, 2000.
We begin the week with the Moon in its waxing crescent phase
descending southward, as it moves progressively against the stars
of Libra, Scorpius, and then far southern Ophiuchus, where it
passes first quarter on Tuesday, September 5th. A couple days
later it bottoms out in Sagittarius, and then once again begins to
climb northward. In the afternoon of Friday the 1st (in North
America), the crescent passes the largest of the asteroids, Ceres.
By evening, the Moon will be a couple degrees to the east of the
famed minor planet.
The most major of the major planets, Jupiter, is majestically
moving eastward against the bright stars of Taurus. On Thursday,
the 7th, Jupiter will pass 5 degrees to the north of the Taurus's
first magnitude star Aldebaran, which itself lies against (but is
not a part of) the more-distant Hyades star cluster. Aldebaran,
Jupiter, and the Pleiades cluster will then create a flattened
triangle, all rising (along with Saturn) shortly before midnight
daylight time. While the two, Jupiter and Saturn, will perform a
slow dance this fall, they will gradually pull apart, Jupiter
heading toward Gemini, while Saturn will linger longer in the Bull.
September is the month for Cygnus, the Swan, the great celestial
bird flying perpetually south along the Milky Way, its bright star
Deneb high overhead in temperate northern latitudes. Cygnus marks
the beginning of the "Great Rift" of the Milky Way, in which the
Milky Way divides into two broad avenues. The Rift is easily seen
from a dark country location in a moonless sky, the western portion
descending into Scorpius, the eastern past Altair in Aquila (the
southern anchor of the Summer triangle) through the heart of
Sagittarius. The Rift and its dramatic extension through the far
southern hemisphere represent the inner disk of our 200-billion-
star Galaxy, which is pervaded by a thin band of obscuring
interstellar dust particles that block the view of distant stars.
The band is highly fragmented into dark clouds and lanes that are
so prominent in the southern hemisphere that the Incas of Peru made
"constellations" of them. It is within these clouds that stars are
born, the birth process hidden by the dark dust.
To the southeast of Cygnus lies Pegasus, its Great Square rising
like a huge diamond. To the left of the rising Great Square find
a string of stars that makes Andromeda, and above its middle the
Andromeda Galaxy, which to the naked eye looks like a faint
elliptical smudge. Photographs reveal dust lanes identical in
nature to those found in our own Milky Way.