Astronomy news for the week starting Friday, October 1, 1999.
The Moon wanes through the week, passing third quarter the night of
Friday, October 1 just about the time of moonrise. With the Sun
still near the autumnal equinox, the third quarter will be close to
the Summer Solstice in Gemini. Watch in the early morning hours as
it wanes through crescent, making lovely triangles with Venus and
the bright star Regulus in Leo the mornings of Tuesday, October 5
(the Moon above the pair) and Wednesday, October 6 (the Moon
below). By the morning of Thursday, the 7th, the Moon will have
moved through Leo, its slim crescent to be seen in twilight to the
right of Denebola.
Though Venus has passed greatest brilliancy for the year, it has
only barely faded and is still overwhelmingly bright in the eastern
sky near dawn. The bright stars of the constellation Leo make a
fine backdrop with which to watch the planet's easterly movement as
it orbits the Sun, Venus now appearing to the right of Regulus.
You do not, of course, have to wait until morning to view a host of
planets. Mars is still with us very low in the early evening
southwestern sky to the east of Antares. Only slowly falling
behind the Earth in orbit, the red planet is pursuing the stars of
Ophiuchus, and will pass into Sagittarius next week. Vastly
brighter, Jupiter rises in the east shortly after sundown, the
giant of the Solar System wading through the dim stars of
southwestern Aries below and to the east of the Great Square of
Pegasus. Coming up about an hour behind Jupiter is doubly-distant
and fainter Saturn, also in Aries, the two planets moving into the
western sky by the advent of dawn.
The Great Square rises like a diamond over the eastern horizon, and
crosses to the south around midnight. Follow the right side
downward and it points nicely to the bright but lonely star
Fomalhaut in Piscis Austrinus, the Southern Fish. Follow the left
side of the Square downward and it crosses the celestial equator
just to the left of the vernal equinox in Pisces and then points to
another lonely star, Deneb Kaitos, the "sea monster's tail," in
Cetus. The northeastern star of the Great Square, Alpheratz, is
one of the few "shared stars," being both part of Pegasus and
Andromeda (and formally in the latter), Andromeda stretching out to
the northeast in a line of bright stars. The other well-known
linking star is Elnath, which makes the northern horn of Taurus and
which is also a part of Auriga (yet formally in Taurus).