SKYLIGHTS
Astronomy news for the week starting Friday, September 14,
2001.
The Moon passes through its new phase this week on Monday the 17th,
rendering the stars wonderfully visible throughout the night
(weather and stray lights permitting). In the morning sky, the
waning crescent puts on a show, when on Saturday the 15th it passes
through the Sickle of Leo, and will be found down and to the left
of brilliant Venus, and up and to the left of the star Regulus.
The waxing crescent will then begin to make its evening appearance
in the western sky the night of Tuesday the 18th. The day before
the new phase, the Moon passes perigee, when it is closest to the
Earth at a distance of only 358,130 kilometers (222,530 miles).
Mercury makes an appearance this week, as it passes greatest
eastern elongation relative to the Sun also on Tuesday the 18th
(when it is down and to the left of the lunar crescent).
Unfortunately, the evening ecliptic lies near its flattest against
the horizon this time of year, so the little planet will appear low
and difficult to see. On Thursday the 20th, Mercury will pass only
a degree to the south of Spica in Virgo. The morning sky again
puts on a better show when Venus passes only half a degree (the
angular diameter of the Moon) north of Regulus, also on the 20th.
We thus have the odd and rare situation where the two stars closest
to the ecliptic -- which hold the autumnal equinox between them --
are being visited by the two inner planets, and not just on the
same date, but at nearly the same moment, about 3 PM Central
Daylight time.
The outer planets are not to be ignored, however. In the evening,
Mars glows in the southwest. Moving easterly against the
background, the reddish planet has shifted into the confines of
Sagittarius. In the morning, Jupiter, second only to Venus in
brilliance, shines high above that planet, with fainter but still-
prominent Saturn higher yet, the two giant planets still in fairly
close proximity.
In the evening, the Summer Triangle, made of Vega, Deneb, and
Altair, are at their best, Vega nearly overhead for those at mid-
northern latitudes as twilight fades. To the north of Vega, find
the two stars that make most of the head of Draco the Dragon, the
pair appearing as the Dragon's baleful eyes. Winding toward the
north, Draco's tail eventually passes between the Big Dipper in
Ursa Major (now going into its autumn hibernation beneath the pole)
and the Little Dipper in Ursa Minor, which in early evening stands
high upon its curved, though faint, handle. the handle ends at
Polaris, which closely marks the North Celestial Pole, about which
the northern sky seems to turn.
