Keeble Observatory
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 http://saturn.jpl.nasa.gov/home/index.html.
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.
Copyright 2004
George Spagna