Astro Bob A look at celestial happenings in the Northland and beyond Bob King View my profile Click here to view previous posts or additional resources

My morning with Comet McNaught

Comet McNaught and a bonus! The comet was just north of the bright star cluster M34 in Perseus (at right) this morning. The long tail is the comet's ion tail. The dust tail is the short "smudge" poking out to the upper right of the green-glowing head. Details: 200mm lens at f/2.8, ~ 3 minute time exposure on tracking mount. Photo: Bob King

Going to bed at midnight and setting the alarm for 2 a.m. seemed like a bad idea, but I did it anyway. When there's a bright comet a-foot, especially one with a tail, I throw caution and sleep to the wind. I packed my gear in the car and drove exactly one block to a location with a great view to the east. There I set up telescope and camera while watching a massive veil of cirrus clouds slowly spread across the sky. With clouds on the loose, the best I could hope for was to catch Comet C/2009 R1 McNaught poking through an occasional sucker hole.

But hey, it was worth the effort. First off, I can say the comet is very easy to see in 10x50 binoculars -- a fuzzy, greenish ball with a bright center that looked like a blurry, out-of-focus star. Because the tail happened to cross over a bright star, it was difficult to see, but I did pick up a trace of it. Clouds also played a part in dimming McNaught's fainter parts. On a pristine morning and without interference from other stars, a short length of tail should be visible in binoculars.

Now it was time for a look through the telescope. In my 15-inch reflector the view was spectacular! The coma or comet's head was very bright and glowed with a blue-green Caribbean sheen, while the ion tail shot straight out of the head to the northwest like the plume from a rising rocket.The thumb-shaped dust tail was a smear of fainter light southwest of the coma.

I didn't expect to see the two tails so clearly. Comets like McNaught that cruise through the inner solar system in the vicinity of the sun often develop both an ion tail, made of gas excited by ultraviolet light from the sun, and a dust tail. Dust tails form from dust kicked off the comet when sunlight vaporizes dirty water ice at and beneath the surface. The ice carries the dust along with it, and the whole works gets pushed back from the comet's head into a tail by the pressure of sunlight. Yes, sunlight has that kind of power, at least when we're talking molecules and tiny dust particles.

Dawn bloomed quickly. By 2:45, darkness was draining from the east as the sky turned pale blue. While looking for a camera lens in the car, I accidentally leaned on the horn. What a shock in the middle of so much quiet! Sure hope I didn't wake up the neighbors at the end of the road.

My head was back on the pillow by 3:30. Looks like I maxed out my sleep account again, but I promise to make it up the next cloudy night.

The International Space Station has returned to the morning sky this week. It looks like a brilliant star moving from west to east either across the southern or northern sky. Here are Central Daylight times for viewing it from Duluth, Minn. and vicinity. To find exact times for your town, please click HERE and type in your zip code.

* Friday morning, June 11 starting at 4:39 a.m. High, brilliant pass across the south

* Saturday, June 12 at 3:33 a.m. Low pass from south to southeast; flys right by Jupiter

* Sunday, June 13 at 3:58 a.m. High, brilliant pass across the southern sky

* Monday, June 14 at 4:25 a.m. Moderately high pass across the north. Midway through its path, the ISS crosses directly in front of the North Star

* Tuesday, June 15 at 3:18 a.m. Passes almost through the top of the sky. A bright one!

* Wednesday, June 16 at 3:43 a.m. Good pass across the northern sky

Posted by: rking@duluthnews.com on 6/9/2010 at 11:21 PM | Comments (0) | Permalink | Edit

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