Astronomy news for the week starting Friday, September 28,
2012.
The week begins with the Moon in its fat waxing gibbous phase ready to go through full the night of Saturday, September 29.
Following full, the Moon then goes into its waning gibbous phase. This full Moon is
special, and is known to all as the Harvest
Moon. With the Sun just past the Autumnal Equinox (in Virgo) and setting nearly due west, the full Moon will
rise nearly due east just past the Vernal Equinox in Pisces. Because of the shallow tilt of the ecliptic as it meets the evening
eastern horizon, there is only a small delay in Moonrise from one
night to the next, which causes a string of early evenings past
full phase to be flooded with Moonlight, just right for the old
harvest time. The night of Wednesday, October 3, the gibbous Moon
will rise to the right of the Pleiades in Taurus,
while the following night finds the rising Moon above Aldebaran and the Hyades and to the west of bright Jupiter. On a
much lesser note, on the night of Saturday the 29th, the Moon
invisibly passes north of Uranus.
Finally, the Moon passes its apogee, where it
is farthest from Earth, the night of Thursday the 4th.
While Mars
still sets half an hour after twilight ends, Saturn is gone.
Wait a bit and then turn in the other direction to see Jupiter
rising about 10 PM Daylight Time in central Taurus to the northeast
of Aldebaran and the Hyades. On Thursday the 4th, the giant planet
ceases its normal easterly movement against the background stars,
entering retrograde motion to the west as the Earth prepares to
pass between it and the Sun. (Which is
what happens to Uranus the night of Friday the 28th as it undergoes
solar opposition.) After a much longer wait you can then see
considerably brighter Venus rising
around 3:30 AM, as it joins Jupiter to make a lovely dawn sight.
The early part of the week finds Venus approaching the star Regulus in Leo from the west. The two then make a fine pairing
the morning of Wednesday the 3rd, when they will be just two-tenths
of a degree apart. Venus then moves quickly to the east of Leo's
luminary, the whole event making it easy to watch planetary motion
in action.
The bright Moon washes out the stars. But you can still admire
those of first magnitude. In early evening find Altair to the south, then Vega and Deneb nearly overhead. The three lie
respectively at the southern, northwestern, and northeastern apices
of the Summer Triangle.
Earlier you might still catch Antares in the twilight southwest,
Scorpius stretching its claws into
now invisible Libra. Fomalhaut then passes low to the
south around midnight. In the morning, Regulus is distinctively
marked by Venus.
