November 2004 Sky from the Keeble Observatory
October's lunar eclipse was mostly obscured by clouds, though you have had a few
brief glimpses. And, while there will be several partial eclipses over the next
few years, our next opportunity to watch a total lunar eclipse won't be until 2008
February 20. (Actually, there will be one on 2007 March 3, but the Moon won't be
above our horizon. If you can get up in the early pre-dawn on 2007 August 28, you
can catch most of the eclipse starting at about 4:00 am.
Cassini has now been orbiting Saturn for four months, and continues to perform flawlessly.
On October 28th the probe flew past the moon Titan at a closest approach of only
750 miles. Cameras aboard the spacecraft were designed with filters to observe at
wavelengths which can penetrate the hazy, dense atmosphere of this enigmatic moon.
As we noted in September, Titan is the only satellite in the solar system with a
substantial atmosphere. Two Voyager probes in the 1980s managed no better than to
confirm that the atmosphere was dense and hazy ... nothing could be seen of the
surface. The atmosphere is mostly nitrogen, which is also true of Earth's atmosphere,
but there's no free oxygen on Titan. It is also extremely cold, fortunately so,
since the moon is not massive enough to hold a warm atmosphere. The haze in the
atmosphere should be methane "smog" ... and Earth-based radar reflected
from the surface told us that there might be pools of liquid methane on Titan. Cassini's
radar may have called some of that into question.
Radar shows large, flat expanses separated by somewhat more rough terrain. The flat
areas appear to be frozen, rather than liquid, though smaller lakes are not yet
ruled out. Vertical relief is no more than 150 feet, and no craters were detected.
The latter tells us that the surface we are seeing is very young. The fact that
Saturn's other moons show lots of craters, tells us that surface processes on Titan
have erased the craters, possibly filled in by hydrocarbons raining from the sky.
Other measurements show that surface winds are comparable in speed to those on Earth,
leaving extensive windblown streaks of material in the equatorial regions.
A separate probe, Huygens, will penetrate Titan's atmosphere and parachute to the
surface in December. You can follow the mission for yourself at
Lunar phases for November: Last Quarter on the 5th, at 12:53 am; New Moon at 9:27
am, on the 12th; First Quarter on the 19th, at 12:50 am; Full Moon on the 26th,
at 3:07 pm.
Evening skies are still effectively devoid of planets. Mercury is barely above the
horizon at sunset, and it will remain difficult viewing, as the plane of the ecliptic
makes a shallow angle with the horizon, keeping it in the haze and clutter. Again,
it is the pre-dawn sky which gives us our view of the planets. Jupiter and Venus
start the month only 3 degrees apart in the eastern sky. Both are very bright, and
on the 4th they will pass less than a degree from one another, an event known as
a conjunction. It should be quite a sight! Jupiter is climbing higher as the month
advances, while Venus settles toward the horizon. Saturn is high to the south, moving
lower and to the southwest by month's end.
Two hours after sunset we find that Cygnus has slipped another 10 degrees towards
the horizon, compared to last month. Its brightest star, Deneb, is now 20 degrees
to the northwest of zenith. The long axis of the constellation is turning towards
the horizon, making it take on its appearance of the "northern cross"
rather than the "swan."
Below Cygnus lies Vega, in Lyra. Also, seeing doesn't have to be perfect for binoculars
or a small telescope to resolve the "double-double" - the modestly bright
star next to Vega - as a pair of close binaries. Binoculars should enable you, on
a clear moonless night, to pick out the faint Ring Nebula, also in Lyra. The finder
chart below was produced with the software package "Starry Night Pro"
- available from Sienna Software. Starting from Vega, you should be able to "star
hop" through the constellation.
Below Lyra, find the faint irregular square of Hercules. Midway between the two
lower stars, your binoculars may enable you to pick out the globular cluster known
as M 13. This system of some 100,000 stars orbits our Galaxy, looking much like
a swarm of dandelion seeds.
For your own monthly star chart, you can direct your web browser to
http://www.skymaps.com. You will find extensive descriptions of what's worth
looking for, and you can download and print a single copy for your personal use.