Skylights featured three times on Earth Science
Picture of the Day: 1
, 2
, 3
, 4
.
Photo of the Week.. A sundog, seen from an aircraft
in deep cold at 30,000 feet, is formed by sunlight refracted by ice
crystals.
Astronomy news for the week starting Friday, December 31, 2004.
We start with the last night of the year, of 2004; welcome to 2005.
To all a Happy New Year to live life and to enjoy the sky.
During the early part of the week the Moon descends through its
waning gibbous phase to its third quarter, the phase reached around noon on Monday January
3rd, about the time of moonset in North America. The Moon then
takes on the stars and planets. The morning of Monday the 3rd
finds the quarter Moon just to the west of Jupiter (which rises just
before midnight), which it passes in daylight (even occulting it in
parts of the eastern hemisphere) and to the south of Porrima (Gamma Virginis), while the
following morning finds the Moon just to the east of the giant
planet (and to the north of Virgo's Spica). Then
it is Mars's turn, the
Moon to the west of the red planet -- and the star Antares in Scorpius -- the morning of Friday the 7th.
Clearly Mars is close to Antares, with which is can be confused
since the colors are similar (though Antares is much the brighter).
Indeed, "Antares" means "like Ares," Ares the Greek version of
Mars. It's a treat to see the two together, Mars just to the north
of the star as the year begins. Saturn, which
is now a prime evening object that rises in mid-twilight, also gets
into the act, passing seven degrees south of Pollux in Gemini on Thursday the 6th (Saturn, Castor, and Pollux making a fine
trio), Mars passing north of Antares the following day. The prize
for "best relationship" though goes to Venus and Mercury,
which as New Year's morning dawns are in tight configuration, Venus
just a degree below much fainter Mercury, both down and to the
right of Mars and Antares. The twilight morning sky does not get
much better.
Early January is host to one of the better meteor showers of the
year, the
Quadrantids, named after the defunct constellation Quadrans
(which is located near the handle of the Big Dipper). The shower
will peak the morning of Monday the 3rd near dawn, though its
typical rate of up to 100 meteors an hour will be quite restrained
by the bright Moon.
Even Earth
involves itself in the New Year, as it passes perihelion --its
closest point to the Sun -- on New Year's Day, when it is 1.7
percent closer than average, at a distance of 91.4 million miles,
or 147 million kilometers. Clearly, given the northern
hemisphere's winter chill, the distance to the Sun has nothing to
do with the
seasons, which are caused by the 23.4 degree tilt of the
Earth's axis relative to the orbital perpendicular.
Nothing quite proclaims the New Year and winter like Orion, the celestial representation
of the ancient Greek Hunter. Already risen at the end of evening
twilight, straddling the celestial equator, Orion crosses the
meridian to the south around 11 PM. Among his best features are
the first magnitude stars Betelgeuse (at the upper left
corner) and Rigel (at lower right),
which bracket the famed "Belt," three bright stars that the ancient
Arabs called the "String of Pearls."
