Skylights featured three times on Earth Science
Picture of the Day: 1
, 2
, 3
, 4
.
Photo of the Week.. Harvesttime Moonset. The dark
band below the Moon is the setting Earthshadow.
Astronomy news for the week starting Friday, October 8, 2004.
The Moon, having passed last
quarter on October 6, wanes in its crescent
phase until it hits new on Wednesday the 13th. At that time it
will pass so close to the
Sun that it will produce a partial
solar eclipse that will be visible near sunset from Hawaii and
far western Alaska, but not at all from the rest of the Americas.
Solar eclipses, while not seen much at any specific location, are
quite common, at least two per year taking place. The lunar
shadow, however, is short, so such eclipses are seen only rarely at
any one location.
Eclipses of the Sun can take place only when the Moon, in its
tilted orbit, passes new phase while crossing the solar ecliptic path. The
alignment will be similar at full phase, so solar and lunar
eclipses go together, and sure enough, we will see a fine total eclipse of the Moon the night of
Wednesday, October 27, one early enough so everyone
can watch, so be prepared!
If you are dedicated (and lucky) you might see an extremely thin
crescent the morning of the Wednesday the 13th in bright twilight
just before new phase. In the days before the eclipse, you can
still watch the thinning crescent pass just south of classical Leo, near Leo's "Sickle," the morning
of Saturday the 9th, to the left of Regulus (and above Venus) the morning of Sunday the 10th, below and
to the left of Venus the following morning, and then just above
Jupiter the morning of Tuesday the 12th as the big planet
starts to climb into morning twilight. With sharp eyes you might
see the Moon actually passing four degrees to the north of Venus in
daytime, as Venus is quite visible in
full daylight (if you know where to look). Venus now rises
just before 4 AM Daylight Time, while Saturn (in Gemini) rises ever earlier, now
coming up just before 12:30 AM. The evening of Thursday the 14th
finds the Moon also in a thin, barely visible crescent, the lunar
disk fattening over the following week.
As autumn deepens we see Cassiopeia
ever higher in the northwestern sky. Following behind it is Perseus, which represents one of the
great celestial heroes, the rescuer of Andromeda, whose star-streams enhance an already
beautiful sky. Much of brilliant Perseus is an actually a cluster, to which most of the
rest is loosely related. Among its Milky Way treasures is the distant, sparkling Double Cluster. Farther to the
northeast is that most northerly of first magnitude stars, Capella of Auriga. South of Auriga and Perseus, find Taurus, the Zodiac's great Bull, which houses
two more clusters, the Hyades
(which makes the Bull's head) and the Pleiades, more popularly known as the "Seven Sisters"
(though but six stars can be seen by most eyes). Watch too for
that great harbinger of late fall, Achernar, which will appear later
at night in the southeast at about the same elevation as Sagittarius, which now escapes to the
west. Below Achernar, if you are far enough to the south, you
might see the stars of Grus the
Crane.
