Sunday, February 8, 2009

Latest Comet Lulin

Well, the weekend is over and while we've been busy, it is hard to point to accomplishments - just running all the time it seems! Astro-club meeting Friday night, mostly finished our hallway painting project and wired new lighting Saturday, dinner with buddy Valerie Saturday night, early Sunday matinee ("Coraline" in 3-D) more shopping at Home Depot, and transporting junk to the front of the house for bulk trash pickup this week. Nothing much exciting to blog about, though when Melinda finishes the trim painting and electrical tomorrow, you will likely see the finished product.

The enclosed photos were taken last Tuesday morning, 3 February when an early morning bathroom visit turned into an astrophoto trip at 3am! I wanted to catch the comet with my 14" Celestron (and Hyperstar attachment), and those predawn objects are hard to catch without a concerted effort. I made a 40 minute trip to the SE side of town off Highway 83 towards Sonoita to get some dark sky in the south. After my 3am wake up, I was exposing 2 hours later...

The first exposure is a quick snapshot of the globular cluster Omega Centauri. Clearing the southern horizon by less than 10 degrees, it was spotted right at the meridian and was an easy target to make sure everything was working. And with 30 second exposures, I didn't have to worry about finding a guide star - the mount was good enough for exposures that short. So while the total exposure is only 2.5 minutes, it still gives an impression of the amazing views that globulars provide. Omega is thought to contain several million stars and is certainly the largest globular cluster in our galaxy. Some astronomers think it may be the remnant of a small galaxy long ago consumed by the Milky Way Galaxy. While visible to the naked eye to the south here in Arizona, it is not visible in the Midwest because it never rises above the horizon.

After those brief exposures of the cluster, it was time to get on the Comet. As mentioned previously, Comet Lulin was discovered in July of 2007 and is currently as close to the sun as it will get. In the next couple weeks it will get another factor of 2 closer to the earth, so is expected to get brighter and on 26 February, will be opposite the sun and visible all night, when it should be barely visible to the naked eye from a dark sky site.

It was readily visible in binoculars, but not detectable to the naked eye. Even a brief exposure with the camera showed the characteristic green color (from dissociated carbon molecules). Because of the comet's motion, when stacking these 6 -2 minute exposures, the stars appear to move. While generally only the brightest comets show a tail, interestingly, this one shows 2, and apparently in opposite directions! The skinny tail to the right is the ion tail being pushed straight back from the comet by the solar wind. The tail to the left are heavier dust particles lagging back along the comets path as it moves, and as we are very nearly in the comet's orbital plane, see this tail apparently pointing towards the sun.

When the comet passes about 40 million miles away from us on the 26th, unfortunately, with the sun directly behind us, the ion tail will disappear behind the comet, but the dust tail may still be visible. Check back in a little less than 3 weeks!

1 comment:

Shannon and Alex said...

I suck. I get on the computer and play when I wake and can't go back to sleep. You head out and take amazing astronomy photos.
Will we be able to see the comet with binoculars?