Photo of the Week. A diffraction corona, caused by
the interference of light waves as they pass by water droplets or
ice crystals thin clouds, surrounds the near-full Moon.
Astronomy news for the two weeks starting Friday, December 4,
The next skylights will appear December 18, 2015.
We begin as always with the Moon, which starts the week just
barely into its waning crescent phase
and almost at apogee (where it is farthest
from Earth), which takes place on Saturday, December 5, with the
Moon just to the west of Mars, the two making a triangle with the
star Vindemiatrix above
them. The Moon will occult (pass in front of) Mars as seen from
parts of the eastern hemisphere, then the morning of Sunday the
6th will appear to the east of Mars, between it and brilliant
Venus. The big event comes the morning of Monday the 7th, when
the crescent will lie barely to the west of Venus as it prepares
for another occultation, which unfortunately occurs during the day
in North America, around 11 AM CST. By the following morning the
Moon will have moved to the other side of the planet. If you have
a good eastern horizon, your last easy view of the slim crescent
will be in twilight the morning of Wednesday the 9th, a couple
days before the Moon passes new on Friday the 11th.
With an equally good western horizon, the Moon will first appear
in twilight the evening of Saturday the 12th. It then grows
through the waxing crescent until it
hits first quarter on Friday the 18th,
as our period comes to a close.
Of the ancient planets, the above three are all we get. But that
should be plenty. Jupiter
, in far southern Leo, rises
first, around midnight, as it makes its transition to the evening
sky. Mars, in the next zodiacal
constellation, Virgo, in
the middle of our fortnight comes up around 2 AM. Last, but
hardly least, is Venus, which vaults above the horizon about two
hours before dawn, by which time Jupiter is close to the meridian to the south, the full parade
consisting of the star Regulus,
Jupiter, Mars, the star Spica,
and finally Venus. Far below is Saturn,
which is not yet high enough at dawn to see.
The nights of Sunday the 13th and Monday the 14th (really the
mornings following) will feature one of the top meteor showers of
the year, the Geminids, which appear to
flow out of the constellation Gemini. Under a dark moonless sky (which we will
have), at their peak the Geminids can produce more than 100
meteors a minute, similar to August's
3200 Phaeton, which was initially identified as an asteroid.
In early evening the constellations of the Andromeda myth are on fine
display. Near the meridian to the south lies Cetus, the Whale or Sea Monster
(his raggedly round head just north of the celestial equator). To the north are
the bright stars of Perseus, the
Hero who rescued the maiden from the monster's jaws.