Photo of the Week. Purple flowers frame a blue sky.
Astronomy news for the week starting Friday, September 23,
2011.
During the early part of the week, the morning skies are ruled by
the slim waning crescent Moon. The
morning of Saturday the 24th, find it rising well below Mars, then the
morning of Sunday the 25th even lower and down and to the right of
rising Regulus of Leo. Unless you are especially
diligent, that will be your last lunar look before the new Moon of
Tuesday the 27th. But then, having passed by the Sun, the Moon
pops up as a thin waxing crescent the
evening of Wednesday the 28th, then grows as it heads toward first quarter next week. Just half a day
after the new phase, the Moon passes perigee, where
it is some six percent closer to us than average, the timing
leading to especially high and low
tides at the coasts.
Jupiter makes something of a transition this week as it rises
around 8:30 PM just as evening twilight comes to a close. Passing
the meridian around 3 AM, by the time
dawn commences the giant planet is well into the west, its location
midway between the flat triangle that makes the classical figure of
Aries and the ragged circle that
represents the head of Cetus, the
Whale. To the east of Jupiter,
Mars begins to climb the sky around 2 AM, an hour or so
before Jupiter transits. Now well into Cancer, the red planet is heading easterly toward the
Beehive Cluster. Finally, the
sky is bracketed this week by the innermost planet and by the most
outerly one that is visible to the naked eye. On Sunday the 25th,
Uranus stands in opposition to the
Sun (rising at sunset, setting at sunrise, crossing the
meridian at midnight), while on Wednesday the 28th, Mercury passes superior conjunction with the Sun (on the
other side of it).
By the time the Sun comes up on Friday the 23rd, it will just
barely have passed the Autumnal
Equinox in Virgo and fall
will have begun in the northern hemisphere. On this day we thus
have just over 12 hours of daylight and the Sun will set nearly due
west. Watch as the points of sunrise and sunset creep toward the
south of east and west as autumn deepens toward winter.
Scorpius, Sagittarius, and the rest of the southern-sky summer
gang now slip off to the west. But memories of summer still last
through the Summer Triangle
of Deneb of Cygnus, Vega (Lyra), and at the southern apex, Altair (Aquila). Look directly north of Altair to find dimmer
Sagitta, the Arrow, and then to
the northwest to admire pretty Delphinus, the Dolphin, which looks like a hand with
its finger pointing back down to Sagittarius.
