Photo of the Week. A white cloud, punctuated by a
distant bird, enhances the color of the blue sky.
Astronomy news for the week starting Friday, September 2, 2011.
Welcome to September, where we will find the first day of fall, the
Sun passing the Autumnal
Equinox on the 23rd. It's a quiet week punctuated by a fine
event. The Moon starts us off with a fat waxing crescent hovering over the early-evening
south-southwestern horizon. With the ecliptic (the plane of the Solar
System) rather flat against the evening horizon, as the Moon passes
first quarter on Sunday, September 4
(around the time of Moonrise in North America), it does not get much
higher as the evenings progress. The evening of Saturday the 3rd,
the Moon will be a bit shy of the quarter, while the next night it
will be seen a bit past it. The Moon then heads into its obvious
waxing gibbous phase as it heads towards
full early next week.
The evening of Saturday the 3rd, for those south of a line from the
northeastern US through Texas the Moon will occult, or pass over, bright
Delta Scorpii (Dschubba), the
middle star of Scorpius's head and
a fine eruptive variable that some ten years ago hit nearly first
magnitude. For residents mostly of the southern and southeastern
US, the star will disappear behind the Moon's dark leading edge
around 9:30 PM CDT, give or take 15 or so minutes depending on
location. For northerners and the rest of the country and Canada,
the Moon will glide just to the south of the star. The following
evening, that of Sunday the 4th, look for the orbiting Moon to be
up and to the left of reddish Antares, while the night of Monday
the 5th, the Moon will bottom out near the Winter Solstice in Sagittarius.
Setting before the end of twilight, Saturn
is pretty much out of it, which leaves three planets to make the
nightly scene. Rising dramatically in the east, Jupiter
, up by 10 PM, tops them all, the giant planet now crossing the
meridian to the south just as dawn
begins to light the eastern sky. Then, just after 2 AM Daylight
Mars makes its appearance in the northeast still against the
stars of Gemini, now just to
the east of Delta Geminorum and to
the south of Castor and Pollux. Number three is Mercury,
the little planet now making an appearance in the east just after
dawn's start and passing its greatest elongation west of the Sun the night of Friday
the 2nd. The morning of Friday the 9th, Mercury will rise less
than a degree to the northeast of Leo's Regulus, the
planet much the brighter.
With the Moon getting brighter, the early-evening Milky Way (descending from Cygnus through Aquila and Scutum to Sagittarius) fades away. Look then for the
Big Dipper going down in the
northwest and for the "W" of Cassiopeia rising in the northeast, the two rounding
the pole -- and Polaris -- opposite each other.