Skylights featured three times on Earth Science
Picture of the Day: 1
, 2
, 3
, 4
.
Photo of the Week.. A "moonpillar," caused by
reflection of light from ice crystals in clouds, rises from the
partially eclipsed Moon during the lunar
eclipse of November 8, 2003.
Astronomy news for the week starting Friday, December 12, 2003.
As the week begins, the Moon wanes toward its last quarter,
achieving the phase around noon on Tuesday, December 16, about the
time it sets (though moonset in daytime is in practice nearly
invisible). The night of Monday the 15th finds the near-quarter
passing to the north of
Jupiter, the two making a fine sight in the sky after midnight.
Jupiter's brother planet, Saturn, was passed
by the Moon last week, and is already up in the northeast by
twilight's end.
As good a sight as this pair is that of
Venus, shining now gloriously in the southwestern evening
twilight sky. Through the telescope, the planet appears in a
gibbous phase, that is, we see mostly the daylight side, less
of the nighttime. Not that it matters much, since Venus is
perpetually surrounded by dense clouds that prevent our seeing any
of the surface. What we know of it comes by means of radar, reflected radio
waves. Climbing ever higher in the evening sky, Venus now sets
about half an hour after the end of twilight. In between, Mars, very visible to
the south, crosses the meridian. Though fading, the red planet, at
magnitude 0, is still brighter than all but a tiny handful of stars
that include Sirius, Canopus, and Alpha Centauri (the last two visible only from quite
far south). Down and to the right of Venus, you might still try
to see
Mercury, always a difficult "find," as it is so close to the
Sun that it is never seen in a darkened nighttime sky. At the
other end of the
Planetary System is Pluto, the smallest "planet" (if you wish to call it
that), which passes conjunction with the Sun at the beginning of
the week.
Though bright Moonlight does get in the way, if you are up in the
early morning hours you might look for some
Geminid meteors, the shower peaking the morning of Sunday, the
14th. The leavings of a comet called Phaeton,
the Geminids -- which seem to come out of the constellation Gemini -- are quite good, at their
best typically yielding over a meteor per minute in a dark sky.
Phaeton is curious. Once thought to be an asteroid, it was found
to have the same orbit as the Geminid shower, and is now considered
a dead comet, its volatiles (which would ordinarily make a tail
under the action of sunlight) either mostly boiled off or crusted
over.
The two stars on the eastern side of the Great Square of Pegasus point southward to Deneb Kaitos in Cetus, and then equally farther
south to Ankaa, the bright luminary
of a deep southern modern constellation called Phoenix -- the "Phoenix" (the legendary Firebird) --
that might be seen gliding just above the southern horizon for
those in mid-latitudes. In between Deneb Kaitos and Phoenix is
very little except for the eastern extension of another modern
constellation, Sculptor (the
Sculptor's Studio). Far brighter are the stars of winter, Orion and its cohort, now rising in
the east as twilight glimmers off to the west.
