January 2008 Sky from the Keeble Observatory
What would you do if you had one last chance to renovate and refurbish your favorite
car, knowing that you would only be able to drive it for another 20,000 miles?
When it was launched in April 1990, the Hubble Space Telescope was hailed as the
greatest instrumental advance in astronomy since Galileo first looked up through
his telescope. Excitement turned quickly to dismay, as preliminary tests revealed
that its 2.6 meter primary mirror was flawed. Ground with high precision to the
wrong shape, (the edge of the mirror was too high relative to its center by approximately
the thickness of a human hair) Hubble began to look like a technological embarrassment.
The cause of the error was a testing “jig” which had been assembled with one component
out of place. Knowing that, and actually having the device available, it became
possible to design corrective optics, which were installed by shuttle astronauts
Since then, the telescope has returned spectacular images and science, more than
living up to its initial promise. Three subsequent service missions have replaced
solar arrays, gyroscopes, and most of the scientific instruments, making Hubble
even more powerful, and earning it a nick-name: the People’s Telescope.
Designed to be serviced and upgraded from the Shuttle, its fate seemed sealed when
NASA administrator Sean O’Keefe decided after the loss of the shuttle Columbia in
2003, that further missions to Hubble were too risky, and that HST would be left
to die in orbit and burn up in Earth’s atmosphere on reentry. Two years later Mr.
O’Keefe’s successor, Michael Griffin revisited the question and convened an expert
panel to fully evaluate risks and benefits. A little over a year ago, he approved
a final mission to refurbish the telescope before the shuttle fleet is supposed
to be retired in 2010. That mission is now scheduled for next August, when Atlantis
will pay its last visit.
Next month, we’ll discuss what changes will be made to the People’s Telescope. It
will be getting more than just new tires!
Lunar phases for January: New Moon on the 8th, at 6:37 am; First
Quarter on the 15th, at 2:46 pm; Full Moon on the 22nd, at
8:35 am. Last Quarter on the 30th, at 12:03 am.
Early morning sky watchers will find Jupiter very low on the southeast horizon,
rising less than an hour before sunrise at the beginning of the month. You’ll likely
only be able to see it if you have a clear horizon and no haze. By the end of January,
it’s lead on sunrise increases to about two hours, but the angle of the ecliptic
is fairly shallow so it still only climbs to about 20 degrees before the sun clears
the horizon. Venus is still the brightest predawn object, beginning the month about
26 degrees above the southeast horizon at sunrise. It will draw closer to the sun
as the month advances, drawing within a degree of Jupiter by the 31st.
Saturn is west-southwest at dawn, 40 degrees above the horizon, above and to the
left of Regulus, in the constellation Leo. It will end the month setting earlier,
about 15 degrees off the horizon at sunrise.
Mars is visible most of the night, beginning the month low to the east-northeast
at sunset. By the end of January, Mars will rise about three hours before sunset,
and will emerge from twilight about 45 degrees above the horizon. Mercury begins
the month low to the west at sunset, reaching maximum eastern elongation and setting
about an hour after sunset on the 22nd.
Our overhead view at mid-month, about three hours after sunset finds the Milky Way
dividing the sky, running from northeast to southwest. It’s hard to see with street
lights and other light pollution, but getting away from the city will allow you
to enjoy this spectacular sight. The brightest star near zenith is Mirfak, in the
Following the Milky Way towards the southeast brings our view past Capella and Elnath,
in Auriga. That’s Mars just below Elnath. (Or, shall we say that Elnath is the star
just above Mars, since the red planet is easier to identify?) Then we turn our attention
to what is, for me, the most interesting part of the sky. Orion, the familiar winter
constellation is clearly visible. That bright red star on his “shoulder” is Betelgeuse
– a red supergiant. This star is about 20 times the mass of our Sun, and if it were
placed where the Sun is, we’d be inside it! Its radius is roughly the same as the
orbit of Mars. It is thought to be near the end of its lifetime, and expected to
end as a Type II supernova – though that even is not expected for millions of years.
Below the familiar “belt” we find the Orion Nebula. This is the closest star-forming
region to the Sun, a stellar “nursery” a mere 1500 light years distant. Binoculars
or a small telescope will reveal the bright Trapezium Cluster illuminating the nebula.
These stars are less than a million years old.
Below Orion we find the brightest star in the night sky, Sirius. This star is actually
a binary, but its companion is a tiny, dim white dwarf which can only be resolved
with a large telescope. Above Orion we find the bright star Aldebaran, marking the
eye of the bull in the constellation Taurus. We also see the nearby open cluster,
the Pleiades. These are young stars, though not as young as the Trapezium cluster
– perhaps ten million years old.
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.