Photo of the Week. Lens like "lenticular" clouds
formed by upwelling waves add a lovely softness to the blue sky.
Astronomy news for the week starting Friday, November 24, 2006.
The Moon begins the week in its waxing
crescent phase as it heads toward first
quarter the night of Monday, November 27th, the exact phase
reached about the time of Moonset in North America, after which it
waxes in the gibbous phase.
Though one is hardly aware of it, the Moon will pass south of Neptune
on Sunday the 26th and then two days later south of Uranus.
For awhile now, all the ancient bright planets but Saturn
have been hovering near
the Sun. This week Mercury breaks out of the
pack, reaching a greatest western elongation of 20 degrees to the
west of the Sun on Saturday the 25th.
Though the angle is far from the possible maximum, the tilt of the
ecliptic relative to the
horizon is such that the planet rises rather well up in morning
twilight fairly far down and to the left of Spica in Virgo. This appearance is rather unusual, in that
Mercury actually rises slightly BEFORE the beginning of formal
dawn. Jupiter
and Mars remain lost
in morning twilight, while Venus
has yet to clear evening's last glow. They will begin to
break out toward the end of the year.
That again leaves the sky to Saturn.
Rising around 10:30 PM, the planet more and more becomes an evening
object. Look for it just to the east of Regulus in Leo, the planet 2.4 times (nearly a full magnitude) the
brighter of the two. Even a small telescope will reveal not just
the rings,
but a small "star" near the planet that is Saturn's largest
satellite,
Titan, the only satellite in the Solar System with a thick
atmosphere, one whose clouds are believed to rain liquid methane.
From mid north America, Cassiopeia
rides high in early evening, while the Big Dipper circles low under the North Celestial Pole, which is marked
nicely by modestly bright (second magnitude) Polaris (the Little Dipper dipping beneath the pole as well). From
the Earth's mid-southern hemisphere, the Big Dipper's disappearing
counterpart is the Southern Cross,
while high up, the two Magellanic
Clouds -- satellite galaxies of ours some 170,000 light years
away -- make a nice appearance, all going around the South Celestial Pole held by dim Octans, the Octant.
