Photo of the Week..
The reddened setting Sun drops toward the horizon. Because we look
through much thicker atmosphere, the lower edge is dimmer and
redder.
Astronomy news for the week starting Friday, October 11, 2002.
The Moon begins our week in its late waxing crescent phase, then
quickly passes through first
quarter the night of Saturday the 12th just about the time of
Moonset in
North America. The night of Friday the 11th, it is about as
far south as possible. Not only does the Moon pass close to the
deep southern winter solstice in Sagittarius, but the tilt of the orbit
takes it even farther to the south. The latter part of the week
sees the Moon climb the sky in the waxing gibbous phase. As our
companion swings northward, it passes south of Neptune
on Monday the 14th, and south of Uranus
the next day, both planets being very close to the ecliptic path.
After a lovely long appearance, Venus is
now effectively gone from the evening skies. But the inner planets
still shine forth, as in the morning, Mercury
makes its best show for the year, when it is seen low in the east
in morning twilight. "Best" is still difficult, as the elusive
planet is so close to the Sun that it can never be seen in complete
darkness. Mercury has been visited by but one spacecraft, and only distant
Pluto remains more mysterious. The giant planets are far more
visible. Saturn
starts the week in its "stationary" mode, and for the remainder of
the year will be in retrograde, or westerly, movement in between
the stars of Taurus and Gemini. Now rising much earlier,
around 10 PM Daylight Time, it beats much brighter Jupiter
by three and a half hours, Jupiter rather dramatically rising
around 1:30 Daylight Time.
The formal constellations number 88, 48 from ancient times. One,
Argo, broken into three, make 50,
then add 38 modern ones, invented between about 1600 and 1800, to
make the full 88. Many more are the informal constellations,
"asterisms" like the Big Dipper,
which inhabits Ursa Major (the
Great Bear) and the Little Dipper, which lies in Ursa Minor. Sagittarius, disappearing now into southwestern
twilight, has a wonderful variety of them. The celestial Archer is
best known for its 5-star upside-down "Little Milk Dipper" whose
handle sticks into the Milky Way. This small dipper figure also
makes the eastern side of the famed "Teapot." Complementing the
teapot is a compact set of stars that lies directly north of the
dipper figure and that represent "the Teaspoon." The neighboring
zodiacal constellation to the east, Capricornus, which now contains Neptune, has no
prominent asterisms, but the next one over, Aquarius, has the prominent four-star "Water Jar," and
the next one Pisces (which
contains the vernal equinox) has
its "Circlet." Aries is bereft of them, and then,
rising over the horizon in late evening is Taurus with its beautiful star clusters, the Hyades (which makes the head of the
celestial Bull) and the Pleiades, or "Seven Sisters."
