Skylights featured three times on Earth Science
Picture of the Day: 1
, 2
, 3
, 4
.
Photo of the Week.. Fuzzy clouds accent a deep blue
sky.
Astronomy news for the week starting Friday, August 20, 2004.
The Moon begins the week just shy of its
first quarter, the phase reached on Monday the 23rd, at which
time the Moon will be 90 degrees to the east of the Sun, rise close to
noon, cross the meridian as the Sun goes down, and set near
midnight. Four days later, the Moon passes perigee,
where it is closest to the Earth. Given that the Sun is about two-
thirds of the way between the Summer
Solstice and the Autumnal
Equinox, the first quarter will be the same fraction between
the Autumnal Equinox and the Winter Solstice, and will appear to
the west of the classic figure of Scorpius, the Scorpion, one of the most prominent
figures of the summer sky.
With the ancient planets clustered fairly close to the Sun, there
is little in between except the most distant of them, Uranus, Neptune,
and Pluto.
Uranus, in Aquarius, goes through
opposition on Friday, the 27th, so it is in prime viewing condition
-- if you can find it. It lies almost directly below the center
star of Aquarius's Water Jar, just to the west of 5th magnitude Sigma Aquarii. At the bright end of
sixth magnitude, Uranus is visible to the naked eye if conditions
are good; binoculars are much better. Good luck! Neptune is in
eastern Capricornus, and for a real
challenge -- if you have a large telescope (or not, it will still
be there) -- Pluto is in southern Ophiuchus just to the northeast of Sabik (Eta Ophiuchi).
Wait until morning and you can see much brighter planets as Venus
and Saturn
(both in Gemini) rise
almost together around 3 AM, Venus beating the ringed planet by
roughly half an hour. Venus's great brightness makes it obvious
almost upon rising. Saturn, over 60 times fainter than Venus, does
not become visible until it is a fair way up. Entirely
invisible,
Mercury goes through inferior conjunction with the Sun (when it
is more or less between us and the Sun) on Monday, the 23rd.
Jupiter is, for now, effectively gone.
As twilight ends, look to the south to find the Little Milk Dipper
of Sagittarius. If your horizon is
flat and clear, you might spot the graceful curve of Corona Australis, the Southern Crown,
directly below it. To the right of Sagittarius, Scorpius is beginning to escape to the
west. Note the middle of the trio that makes the Scorpion's head,
Dschubba (Delta), which has
brightened notably almost to first magnitude as it mildly erupted
and tossed off a surrounding shell of gas. The stars are not quite
as constant as they might seem. Then of course admire the great
red supergiant Antares, which
will most likely explode sometime in the distant future. Above
Scorpius are Ophiuchus, the
Serpent Bearer, and the great Serpent (Serpens) that he holds, the figure bridging the gap
between the Scorpion and Hercules
to the north.
