Photo of the Week. Squashed sunrise, the Sun
distorted by atmosphric refraction, which raises the lower edge
farther up than the upper. As the Sun climbs, the effect rapidly
disappears.
Astronomy news for the three week period starting Friday, December 24, 2010.
First up, the Moon. It starts the triple week in its waning gibbous phase, then passes through third quarter on Monday, December 27, as it
makes the transition to morning's waning
crescent. New Moon is hit on
Tuesday, January 4, the Moon then moving into the evening sky as a
waxing crescent that heads toward first quarter on Wednesday the 12th. At the
end of our period, we get to see a bit of the waxing gibbous.
As it goes, the Moon first meets Saturn the night of Tuesday
the 28th, gliding 8 degrees to the south of the ringed planet.
Then watch as the waning crescent passes down and to the right of
Venus New
Year's Eve, and then celebrates New Year's day by joining up with
the star Antares, after which it
drops below Mercury.
Finally, the waxing crescent appears several degrees northwest of Jupiter (and Uranus) the
evening of Sunday the 9th, then to the northeast of them the
following night. The Moon passes perigee, where
it is closest to Earth, on Christmas Day, then apogee the night of
Sunday the 9th.
The planets play their own games. After a long wait, Jupiter
finally passes by Uranus on Sunday the
2nd, the two a mere 0.6 degrees apart, Jupiter to the south.
Setting ever earlier, by 11 PM at the year's start, the giant plant
nicely hovers in the western evening sky as darkness falls. For a
time it is replaced by much dimmer Saturn, which by January 1 rises
half an hour after midnight (shifting to midnight by January 9),
still in Virgo, still to the
northwest of Spica. Venus,
brilliant in morning's light, makes a bigger splash. Rising before
4 AM, our closest neighbor passes greatest western elongation (48
degrees) with the Sun on Saturday
the 8th. Mercury follows the next day, but at 23 degrees western
elongation is far to the east of Venus and not far above the
horizon during dawn. Not that anyone will notice, but
Pluto goes through conjunction with the Sun on Sunday the 26th.
Four more events highlight our trio of weeks. First, the Earth
passes perihelion, where and when it is closest to the Sun (91.41
million miles, 147 million kilometers, 1.7 percent below average)
on Monday the 3rd. Obviously, distance to the Sun has nothing to
do with the seasons (but every bit
with the 23.4 degree tilt of its axis against the revolutionary
perpendicular). Two days later, as a result of this tilt and the
Earth's orbital eccentricity, we bottom out with the mid-northern
hemisphere's latest sunrise of the season. Third, the new Moon
will pass across the Sun for a
partial eclipse. But don't look for it, as it is strictly a
European/Asian/African event. Finally, you might watch for the Quadrantid meteor shower (named after the defunct
constellation Quadrans, the Quadrant, which mostly lies in
northern Bootes to the east of the
Big Dipper's handle), which will
peak around January 3-4. In a dark sky, you might see as many as
one or two a minute.
Orion of course now dominates the
late evening sky, its two brightest stars, Betelgeuse and Rigel, standing out like orange-red
and blue-white jewels. To the northwest of Rigel find dimmer Cursa, the source of Eridanus, the celestial River, which
ends far below northerners' southern horizon in brilliant Achernar.
