Just in time for the holidays Earth has a celestial visitor!
Comet Wirtanen makes one of the closest approaches ever recorded. It’s a small
comet with a short orbital period of 5-6 years. It is bright enough to see with
the naked eye, although because of its small size the way it scatters light, it
is hard to spot. Keeping with the holiday tradition, if you’re lucky enough to
see it, it will appear to be green.
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| Wirtanen approaches, as seen in November (NASA) |
I am sadly surrounded by street lights, so I had to take a short
trip to a state park where I had a dark sky. With a spotting scope and a
general area of where to look, I was unable to find Wirtanen. The comet makes
its closest approach to the sun tonight, and I decided to try again. However, I’ve
been blessed with clouds. My next chance is Saturday night, when it is closest
to Earth. Of course, rain is in the forecast.
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| Geminids (Smithsonian Magazine) |
While I failed in my attempt to see just my second comet, I
happened to see a meteor streak across the sky. Meteor showers are bits of
cometary debris burning up in the atmosphere as Earth passes through the comet’s
debris field. Comets are just dirty snowballs that melt a little bit as they
approach the sun. As they break up, all the pieces that break off trail behind
and wait for our orbit to sweep them up. This meteor was not associated with
Wirtanen. It was part of the Geminid meteor shower, which is debris from the
comet 3200 Phaethon, a dead comet. Its ice has melted and all that remains is
rock. Most likely, if we ever pick up all the debris then there will be no more
Geminids.
If you want to try your luck at finding Wirtanen, here’s a
handy link that shows its location throughout the month. This month's information is from StarDate and NASA.