Photo of the Week. In honor of winter, Skylights
presents the first of a 12-part "flight across Greenland," going
from east to west. See full resolution.
Astronomy news for the two weeks starting Friday, December 20
2013.
The next Skylights will appear Friday, January 3. Happy Holidays
and clear skies to all.
And the Season is celebrated nicely by the Moon. It begins our
fortnight in its waning gibbous phase,
which ends at third quarter on Christmas
morning, after which it fades in the waning crescent until New Moon
on New Years' day. Christmas night, the quarter will be seen a few
degrees south of Mars, while the
following night it will be to the north of the star Spica in Virgo. Then the morning of Saturday the 28th, the Moon
will shine just to the west of Saturn, while
the following morning it will have switched to the east of the
planet. By the morning of Monday, December 30, you'll find the
thin crescent to the north of the star Antares in Scorpius. After new, the evening of Thursday, January
2, we get to see a wisp of the waxing
crescent in western evening twilight well above Venus, which is
dropping quickly down toward the horizon as evening falls and the
month proceeds.
Venus is nicely replaced by Jupiter. Rising
around the end of twilight, the giant planet dominates eastern
skies, then crosses the meridian to
the south shortly after midnight and just after Mars rises in the
east well into Virgo. Mercury
celebrates your author's birthday (thank you thank you) by passing
superior conjunction with the Sun
(on the other side of it) on Sunday
the 29th.
The double week starts off nicely with the Sun crossing the Winter Solstice in Sagittarius at 11:11 AM CST (9:11 AM
PST, 12:11 PM EST, etc.) on Saturday the 21st, whence beginneth
astronomical winter and the Sun starts moving north. But as
Grandma said, "as the days begin to lengthen, then the cold begins
to strengthen," at least in northern climes. New year's day is
busy, as we have not only new Moon, but we find the Moon passing perigee (closest
to Earth) and Pluto in
conjunction with the Sun. Moreover, the Earth passes perihelion,
where it is closest to the Sun on its slightly elliptical orbit
(1.7 percent closer than average), early next week on Saturday the
4th. The combination will bring especially high tides to the coasts (though not to the
midwest).
In late evening, Orion hunts
about halfway up the sky. Look carefully at the colors of his two
brightest stars, reddish Betelgeuse (at upper left) and
blue-white Rigel (at lower right),
both of which are evolving supergiants. Both are
destined someday to explode as supernovae. Coming off
Rigel to the west meanders one of the longest constellations of the sky, Eridanus, the River, which ends deep
in the southern celestial hemisphere at brilliant Achernar.
