Photo of the Week. Great Orion rises from his slumber, the reddish Orion Nebula just clearing the trees.
Astronomy news for the week starting Friday, December 14, 2007.
We start, as always, with the ever-popular Moon, which begins
the week well along in its waxing crescent
phase. Passing first quarter on Monday the
17th, it then enters the waxing gibbous
as it heads toward full next week. On
Sunday the 16th, the Moon will pass north of Uranus, which still
hangs out in eastern Aquarius to
the southwest of the Circlet of
Pisces.
Four planets plan big events. At the bottom of the list is Pluto, which passes conjunction
with the Sun on
Thursday the 20th, making it REALLY invisible. Next up is Mercury, which also passes
conjunction with the Sun, on Monday the 17th. Given its position
inside the Earth's orbit, it
(like Venus
) can go through two kinds of conjunctions, one when it is
between us and the Sun, an "inferior conjunction", the other (like
this one) when it is on the other side of the Sun, a "superior
conjunction." Saturn then
comes forward by entering
retrograde, or westerly, motion against the stars on Thursday
the 20th, as the Earth prepares to swing between it and the Sun.
Watch for the ringed planet's rising in southern Leo around 10:30 PM.
The week, indeed the rest of the year, however, really belongs to
Mars,
which in this orbital round makes its closest approach to the Earth
on Tuesday the 18th, when it is 0.589 Astronomical Units (88.2
million kilometers, 54.8 million miles) away. It is also then at
its brightest, just a hair brighter than the brightest star, Sirius. Mars reaches opposition with
the Sun on December 24th. That closest approach does not occur at
opposition is the result of Mars's rather eccentric
orbit. Near opposition, the red planet now rises in southwestern
Gemini just after sunset and
crosses the meridian high to the south
about half an hour after midnight.
All of this activity is watched by far-brighter Venus, who still
brilliantly glorifies the southeastern morning sky, rising just
before 4 AM. And by Comet
Holmes. Still in Perseus,
it remains a nice binocular object.
It's more than past time to note the rising of Orion, who lofts himself above the
eastern horizon as twilight draws to a close. Look for his three
star belt and the two first
magnitude supergiants, Betelgeuse, to the northeast of
the belt, and Rigel (actually
zeroth magnitude) to the southwest.
