January 2007 Sky from the Keeble Observatory
Some random notes:
NASA has announced preliminary plans for a permanent base on the
Moon, possibly by 2020. With the shuttle fleet to be retired in
2010, after completion (or not) of the International Space Station,
and the next generation of crewed vehicle not planned for launch
before 2014, I wouldn’t hold my breath anticipating that it
will really happen. Indeed, with three presidential and six congressional
election cycles between now and then, it’s likely to go the
way of the first President Bush’s vision to return to the
Moon as a precursor to a Mars mission.
Last month’s adieu to the Mars Global Surveyor was not the
end of important results from that long-lived orbital probe. Researchers
have published findings of recent outflows of liquid water on Mars.
That Mars was warmer and wetter in its distant geological past is
generally agreed. Most planetary scientists, however, were reasonably
certain that the remaining water should be found frozen in the polar
caps. Atmospheric pressure is so low that liquid water would simultaneously
boil and freeze if released onto the surface. Images of several
craters, taken at five year intervals, show what appear to be fresh
deposits of light colored material in gullies. These deposits appear
to flow around obstacles and, in at least one case, out onto the
floor of the crater. The simplest explanation is that this was caused
by a brief burst of running water from some underground aquifer,
which left behind surface deposits of salt and possibly some ice.
It’s not a landslide, since we’ve found that the sub-surface
material on Mars is actually darker than the undisturbed surface.
For what it’s worth, the entire 10-year Global Surveyor program
cost less than a single shuttle mission.
Lunar phases for January: Full Moon at 8:57 am, on the 3rd; Last
Quarter on the 11th, at 7:45 am; New Moon on the 18th, at 11:01
pm, and First Quarter on the 25th, at 6:01 pm.
Predawn planet watchers will have some good targets this month.
Saturn, which rises in early evening, is still visible to the west
at sunrise. As January progresses, look for it closer and closer
to the horizon, beginning the month at about 35 degrees altitude,
settling to about 10 degrees by month’s end. Jupiter and Mars
are visible in the southeast at sunrise. Jupiter rises about 2 hours
before the Sun on the first, 4 hours by month’s end. Mars
is about an hour ahead of the Sun all month.
After a long autumn with almost no planets to be seen in the evening,
sky watchers will have more to see this month. Venus has moved back
to the east of the Sun, so it appears as an “evening star”
to the west. Look about 10 degrees above the horizon early in the
month – it sets about an hour after the Sun. By month’s
end it climbs higher, setting about 2 hours later than the Sun.
Also returning by late January is Mercury, about halfway between
Venus and the Sun in the western sky. Saturn rises about 4 hours
after sunset on the first, but earlier and earlier as the month
advances. On the 31st it will rise only an hour after the Sun goes
At mid-month, two hours after sunset, looking directly toward zenith
finds the constellation Perseus overhead. The most prominent constellation
to be seen for the winter season is Orion, to the southeast. Working
towards Orion from zenith, we encounter the Pleiades cluster. This
is a so-called “galactic cluster” or “open cluster,”
which only means that it’s in the disk of the Galaxy rather
than orbiting in the halo. This cluster is about 400 light years
distant, and a relatively young 10 million years in age. Binoculars
or a small telescope will reveal more than the familiar “seven
sisters” in the familiar shape of the Subaru logo.
Below and a bit to the right of the Pleiades lies the bright red
star Aldebaran in Taurus, from an Arabic word meaning “follower.”
The Bull is following the Seven Sisters across the sky. This star,
about 65 light years distant, is a “red giant” –
a star of roughly solar mass but ballooned out to about 40 solar
radii. It’s actually a binary, with a faint red dwarf companion
We come to Orion, and note the red star on the upper left of this
familiar constellation. This is Betelgeuse, from another Arabic
word meaning “hand of the Central One,” a red supergiant.
1 AU is the average distance from Earth to Sun; this star’s
radius is on the order of 2.8 astronomical units! The distance to
Betelgeuse is about 425 light years. Comparing its apparent brightness
to Aldebaran, we can see that its greater distance requires its
intrinsic brightness must be much greater – about 60,000 times
as luminous as the Sun.
Next month we’ll look in detail at some of the other bright
stars in Orion.
For your own monthly star chart, you can direct your web browser
You will find extensive descriptions of what's worth looking for,
and you can download and print a single copy for your personal use.