The Sky is Falling!
updated: Mar 09, 2013, 10:00 AM
By Chuck McPartlin
Comets on the way to Santa Barbara skies.
Comets are icy dirtballs in space that can put on an impressive show when their orbits bring them close
to the Sun and their volatile materials sublimate into vapor. These gasses, plus the bits of dust that
spray away with them, often form two visible tails which point away from the Sun. The ion tail glows a
fluorescent blue as charged particles in the solar wind sweep ionized gasses directly outward in the
A yellower dust tail curves away as the particles are left behind in their own new orbits around the Sun.
Here's a photo of Comet Hale-Bopp in 1997, looking like it's about to visit my uphill neighbor.
You can see where the word comet, or "hairy star", came about. Hale-Bopp was the last great comet that
we saw from Santa Barbara. Since then, it seems like the southern hemisphere was getting all the luck.
That may change this year, with two potentially bright comets heading our way.
The first to arrive is coming the week of March 10, and is already a naked-eye sight in the southern
hemisphere. It's Comet C/2011 L4 Pan-STARRS, named after the telescope and observing program that
discovered it - the Panoramic Survey Telescope and Rapid Response System. A major goal of the Pan-
STARRS program is "to discover and characterize Earth-approaching objects, both asteroids & comets,
that might pose a danger to our planet". After the big Chelyabinsk meteor event last month, a
lot more people are paying attention to this sort of thing, at least until funding is required. The B612
Foundation is looking at ways to find and deflect potentially hazardous objects.
The comet will be low in our western sky after sunset, and the brightest part, called the coma, should be
visible without optical aid. The views will be best through binoculars. Here's where to look for the
comet, with the Moon serving as a guidepost. The positions are for 7 PM PDT (we switch on March 10) of
March 12 through March 19, with the comet and Moon shown for March 14. I think the depiction of the
length of tail visible is a bit optimistic, but with comets you never really know until it happens. At
any rate, Edhat photographers should get out and shoot some nice images.
Pan-STARRS isn't really a great comet on a par with Hale-Bopp, but there is another comet coming up in
late November that may be rather spectacular. Of course, it could also fizzle like Kohoutek in 1973.
Comet C/2012 S1 ISON was discovered by two Russian amateurs working with the International
Scientific Optical Network. It seems to be a first-time visitor to the inner solar system, so it may have
lots of pristine volatiles that will put on a good show, potentially reaching a brightness that would make
the coma visible in daylight. Now that would be a great comet! As it swings around the Sun, its tail may
be big and bright enough to be seen in both the predawn and sunset sky.
Looking even farther ahead, Comet C/2013 A1 Siding Spring has an orbit that will bring it very close to
the planet Mars in October of 2014. It will probably not impact Mars, but the Curiosity rover may get
some fantastic views.
Links for comet information:
The B612 Foundation
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