Photo of the Week. An intense partial rainbow seems
to shoot from the sky.
Astronomy news for the week starting Friday, September 10,
2010.
The Moon, having passed its new phase late last week, is now in a
growing crescent nicely visible in evening
as it heads towards first quarter on
Tuesday, September 14th, about the time it sets in the southwest,
after which it waxes in its gibbous phase.
You may be able to spot the slim crescent the evening of Friday the
10th as it glides beneath
Mars and the star Spica (Mars
the fainter of the two), with Venus up and to the
left of the Moon. Then the night of Saturday the 11th, it will
shine nicely to the other side of the bright planet, the two having
switched places. Look early in twilight. The waxing crescent then
meets up with Antares in Scorpius, seen closely to the west of
the star the evening of Monday the 13th, but well to the other side
the following night. The Moon actually passes directly over Venus
on Saturday the 11th, but during the day and out of sight for North
Americans.
We speak of looking at Mars, but it's now a tough find, though
Venus is readily still visible in twilight. Indeed, it's still
brightening as it closes in on Earth, and will until the 23rd.
Sadly, we are in an unfortunate position in that the tilt of the
solar path -- the ecliptic --
which the planets pretty much follow as well, lays rather flat
against the horizon, which keeps Venus very low after darkness
begins to fall.
But not
Jupiter, which now dominates the later evening sky, the planet
rising around 7:30 PM Daylight Time, before the end of twilight and
Venus-set. By 1:30 AM it is crossing the meridian to the south, then remains up in
the southwest the rest of the night. The planet's main moons can
be seen in steadily-held binoculars. Though the giant of the
planetary system, Jupiter still carries but a thousandth the mass
of the Sun. Slowly moving
retrograde (westerly against the stars), the planet is gliding
just a degree or two south of the Vernal Equinox in western Pisces.
In other hot planetary news,
Mercury becomes visible in eastern morning twilight below
Regulus,
while very dim Pluto, in Sagittarius, ceases its backward movement and begins
direct easterly motion on Monday the 13th. Not that you'd much
notice, as the little "ex-planet" moves only a bit over a degree
per year. But it makes a good time to celebrate the life of its
discoverer, Clyde Tombaugh.
As the Dipper rolls down the
northwestern sky, its opposite, Cassiopeia, the Queen of the Perseus myth, rises in the northeast, the constellation easily distinguished by
its famous "W" shape. Behind it follow Perseus itself and the rest
of the gang, dim Cepheus (who
is pretty out of the myth himself) in the lead.
