Friday, January 22, 2010

Blast From The Past!

Three years ago yesterday, I was chasing lights in the sky. If you had seen these in the western sky, would you know what you were seeing?

Well, I won't keep you in suspense - it was from the comet of the still-young century, Comet McNaught! For weeks before hand, many observers saw it low in the southwest as it approached the sun. It brightened steadily, never straying far from our star till it exited into the Southern Hemisphere sky. Some observers even saw it in the daytime, but I was in the Midwest, visiting Melinda, and we didn't have any breaks in the clouds for my week-long visit.

Upon my return to Tucson, I had heard that even though the main part of the comet was spectacular in Southern Hemisphere skies, parts of the tail were visible in northern latitudes as well. We had clouds too, but on the 21st of January, there were some breaks in the western sky, so I loaded the van and headed out towards the base of Kitt Peak, where there was a temporary hole in the clouds. In the west the crescent Moon and Venus were setting. Suddenly the strange, contrail-looking glows appeared in the darkening sky superimposed on the Zodiacal Glow in the west - the tail of McNaught! The "streaky" features are called synchrones and are not-well understood features that develop in the tails of bright comets.

I was able to take a couple exposures with a 16mm fisheye (pictured at top), and 2 frames with a 50mm lens that I stacked for the exposure at left. Shortly afterwards, the clouds moved in and that was that. A few days later, with the Moon even higher and brighter, I went back out, and still detected the tail, but it required many exposures, stacking them, and stretching the contrast to see it. Meanwhile the show continued in the Southern Hemisphere.

This photo, taken by the comet discoverer himself, Rob McNaught in Australia, shows the comet about the same time as the photos above. Note how the striations in the tail bend down and disappear below the horizon at right. Well, if you can imagine me up in the Northern Hemisphere over that horizon, the continuation of the tail was visible, without the body or head of the comet above my horizon. This photo was the Astronomy Picture of the Day for 22 January, 2007.


Jeremy Perez said...

Great photos Dean! They're beautiful. I remember observing the very subtle synchronic bands with Brent Archinal out at Wupatki National Monument on Jan 20. My camera batteries died after one shot, so my only photo was horribly noisy, so the sketch came out better. What an amazing thing to see. Thanks for sharing the images, and the reminder of a wonderful event.

David A. Harvey said...

Awesome Dean! Yep - remember that comet. Remember seeing it in broad daylight. Took some pics of it through the Questar. I'll have to try and find them . . .