Astronomy news for the week starting Friday, July 31, 2009.
The Moon waxes through its gibbous phase the early part of the week as it
moves towards full, which takes place the
night of Wednesday, August 5, shortly before moonrise in North
America. During the remaining couple days of our week it then wanes as a fat gibbous. Almost exactly two
days before full, the Moon passes through apogee, where it
is farthest from the Earth. The night of Friday the 31st, the Moon
finds itself just to the east of Antares in Scorpius.
This full Moon, the "Green Corn Moon," the "Grain Moon," has a
couple extra features associated with it. First, well in the
southern Zodiac in Capricornus, it will appear just to
the west of Jupiter, the two making a nice pairing. Then it
slightly passes through the partial shadow of the Earth for a
penumbral
eclipse (August 6, Universal Time), much as it did the night of
July 7, giving us two in a row, an infrequent occurrence. But as
for the last one, don't expect anything much. Someone on the Moon
would see the Earth taking only a bite out of the Sun, the amount
of light lost rather minimal. From here we will see almost
nothing, and then only over central and eastern North America just
after Moonrise. The next "real" eclipse will take place on
December 31, and that will be just barely partial and visible only
throughout Europe, Africa, and South America. Passing north of
Jupiter during daylight on Thursday the 6th, by the time it rises,
the waning gibbous will then appear to the east of the giant
planet. That same night, the Moon also passes a few degrees north
of Neptune,
the sight quite invisible.
Our observation running from evening to morning, Mercury is
making a poorish appearance in the west, appearing as a binocular
object low above the western horizon in early twilight. On Sunday
the 2nd, the little planet will pass half a degree north of Regulus in Leo. Somewhat to the east, also in twilight, you can
still see Saturn, the
ringed planet setting as twilight draws to a close. Then switch
your view to the southwest to watch Jupiter climb the sky as it
nears opposition to the Sun.
Later that night, as Jupiter crosses the meridian to the south just before 2 AM
Daylight Time, Mars
rises to the northeast of Taurus's Hyades and
Aldebaran, the easterly motion
of the planet against the stars quite obvious over the week. Now
caught between Taurus and Gemini, brilliant
Venus then lofts itself up a bit later, around 3 AM
Daylight.
With Leo disappearing in western twilight, shift your view next
along the Zodiac to Virgo with
bright Spica. Jumping over dim Libra, not very visible under near
full Moonlight, the next step is Scorpius with bright Antares,
which accompanies the Moon as our week begins.
