Photo of the Week. Here comes Comet Holmes. The picture is centered on Mirfak, Alpha Persei (the brightest
star of Perseus). The comet, seen
the night of October 31, 2007, is the bright "star" down and a bit
to the left of Mirfak (near the lower edge of the picture). Holmes
is here near its brightest following its late October outburst, and
is beginning to show some fuzzy structure.
Astronomy news for the week starting Friday, December 28, 2007.
Happy New Year to all and best wishes for a great 2008.
As always, we begin with the ever-shifting Moon, which celebrates
the coming end of 2007 by passing through third quarter the night of Sunday, December
30th. The pair of days before that event, the Moon will be in its
last waning gibbous phase, while the New
Year begins with the Moon in the waning
crescent. The week concludes with the Moon passing through apogee
(actually on Wednesday, January 2), where it is farthest from
Earth.
As the year begins,
Mars now rises at the Gemini-Taurus border
just before sunset, gloriously transiting the meridian just after 11 PM. Mid-evening
sees Saturn,
still in Leo, rising at 9:30, then
transiting at 4 AM, half an hour before Venus rises in the
southeast.
The Big Event is the passage of the Earth through its
perihelion point the evening of Wednesday, January 2, at 6 PM
Central Time. At that time it will be closest in its orbital path
to the Sun, a distance of 0.983 Astronomical Units (the average
Earth-Sun distance), or 147 million kilometers, 91.4 million miles
(98.3 percent closer than average). That perihelion takes place in
the dead of northern winter clearly shows that the distance between
the Earth and Sun has little if any effect on the
seasons, which are caused by the 23.4 degree tilt of the
Earth's rotation axis relative to its orbital axis. The
seven percent variation in solar heating between perihelion in
January and aphelion (farthest from the Sun) in July is quite lost
in the distribution of Earth's oceans and land masses. The closeness
of perihelion passage to New Year's Day is pure coincidence.
The other Big Event (there are two) is one of the best meteor
showers of the year, the Quadrantids (named
after the defunct constellation Quadrans, the Quadrant, just to the
east of the Big Dipper), which
peaks the night of Thursday, January 3 - the morning of Friday,
January 4, when you might see up to 100 meteors per hour, the
crescent Moon not much of a hindrance. The best time is predicted
to be 12:40 AM CST.
As the New Year progresses, the autumnal stars of the
Perseus Myth begin to move into the western evening skies.
Look for Perseus himself nearly
overhead between 8 and 9 PM. To the west lies Cassiopeia, the Queen, while farther over is the dim
pentagon that makes her husband, Cepheus, the King.
