Skylights featured three times on Earth Science
Picture of the Day: 1
Photo of the Week.. The full Moon and the Earth's
shadow set to the west in early morning twilight.
Astronomy news for the week starting Friday, January 17, 2003.
Moon sails across the sky during the early part of the week,
the exact phase reached on Saturday, the 18th, around the time of
Moonset in the Americas, causing the Moon to set almost exactly at
sunrise. The night of Friday the 17th, the near-full-Moon will rise
just before sunset, the following night just after. Since the
Earth has just passed the winter
solstice in Sagittarius, the
full Moon will reside just to the east of the Summer Solstice, which places it nicely among the stars
of Gemini just to the south of
Castor and Pollux. Toward the latter part of
the week, on Thursday, the 23rd, the Moon passes perigee, where it
is closest to the Earth. As our companion wanes through its
gibbous phase, rising ever later, it passes north of Jupiter during the day
of Sunday, the 19th. The Moon will therefore be just to the
northwest of Jupiter the night of the 19th and to the northeast of
the giant planet the night of Monday the 20th.
Full Moon is the best time to admire the extent of the lunar
"seas," the "maria," which are made not of water, but are
shallow oceans of dark solidified lava that fill huge impact
basins. These spots, all of which are named, make the "man in the
Moon" and other fanciful figures. That we see them always in the
same position shows that the Moon rotates such that it keeps one
face pointed toward Earth at all times, the result of tides raised
by the Earth on the Moon.
Four planets are now readily visible, Jupiter (well marked this
week by the Moon), Saturn, which sits high in Taurus rather well to
the west of Jupiter and just to the northwest of Zeta Tauri, brilliant Venus,
which outshines everything in the pre-dawn morning sky except for
the Moon itself, and much fainter Mars, which falls due west of Venus and to the
northwest of Scorpius. The others
are tucked in too close to the Sun, with the exception of Pluto, which is far too
faint to be seen without substantial optical power. The little
planet is in the morning sky, Mars, Venus, and Pluto all rather in
ordered line and angularly equidistant from each other.
The autumn constellations, including the great figures of the Perseus myth, are slowly making their
exit. As the sky darkens, Andromeda and Pegasus are to the west of the meridian, while the
villain in the story, Cetus the
Whale or Sea Monster (who is to devour Andromeda) lies due south.
While not a brilliant constellation, the Whale's rather circular
head stands out nicely to the southwest of Taurus. Far to the north of it are the graceful curves
that make Perseus, the slayer of Cetus, while to the south lies the
western bend of Eridanus, the