Skylights featured five times on Earth Science
Picture of the Day: 1
, 2
, 3
, 4
, 5
Photo of the Week.. Dramatic cloud shadows proclaim
the glory of the sky.
Astronomy news for the two week period starting Friday,
September 23, 2005.
Skylights now resumes its normal weekly schedule.
We start the week with the Moon not quite in its last
quarter, the phase reached the night of Saturday the 24th about
the time of Moonrise in North America. The remainder of the week
is spent in the waning
crescent phase as new Moon is approached. By the end of the
week, the Moon will appear as a slim crescent in the eastern dawn
sky. The only lunar passage of note is that between the Moon and
Saturn, our
companion gliding north of the ringed planet the night of Tuesday
the 27th, though you will not see the event until Saturn rises
around 2:30 AM, Daylight Time. Just half a day after this
visitation, the Moon passes apogee,
where it is farthest from the Earth in its monthly round.
With Jupiter setting in mid-twilight and pretty much out of
sight, the early evening belongs to brilliant Venus, which, while
shifting south, is getting marginally higher (for the same interval
after sunset) and not setting until a bit after twilight is over.
But around 9 PM, half an hour after Venus leaves us, Mars ascends the
eastern sky as it prepares to move from eastern Aries into western Pisces. The red planet, now brighter then the
brightest stars, then holds forth until the rising of Saturn.
Barely moving against the background stars, Mars begins retrograde
motion on Saturday, October 1, just after Skylights' current week
comes to an end.
The Sun, having just
passed the autumnal equinox, while always moving a degree per day
to the east against the background stars, is also moving as rapidly
as possible to the south, at a rate of about four-tenths of a
degree per day. The effect is very noticeable in the day-to-day
times of sunrise and sunset, sunrise quickly coming ever later,
sunset earlier, the points of sunrise and sunset now just to the
south of due east and west.
Early September is a time to praise the Milky
Way, the great white band that is made of the combined light of
the billions of stars in the disk of our Galaxy. Bright city skies
make it difficult, if not impossible, to see, but viewed from the
dark countryside, it is spectacular and deeply moving. Watch it
come out of the northeast through rising Cassiopeia, then climbing nearly overhead as it passes
through Cygnus and across its
bright star Deneb. Splitting in
two as a result of the dark dust clouds in the Galaxy's plane
(where stars are born), the Milky Way plunges south through Aquila, Scutum, and Sagittarius, where it has its heart, only to disappear
-- for unlucky North Americans -- below the southern horizon.
