Another Cometary Blast From the Past!

While on vacation a couple weeks ago, I got an e-mail from a book publisher looking for permission to use one of my photos in a text. This is now the second request I've gotten in the last 14 months while in the middle of a month off where I didn't have a backup of my images with me. My images aren't that popular, in fact these last 2 requests have been the only ones in recent memory. The last time this particular image was used was back in film days, and in any case, I didn't even have a scan of the original to send them. So after a search for the slide and a run to the lab to get a scan, I've got a pretty cool shot of Comet Hale Bopp from March, 1997. I need to think about scanning other favorite images from that era...

It was a time I remember well! I had just gotten a Schmidt camera, so I had the perfect camera to record a wide field with short exposures. The comet first appeared in the morning sky, so at it's peak, I was making 3am trips up to Mount Lemmon's Geology Vista to set up gear, take a couple exposures, drop off the film on the way to work, pick up at noon. If they were great, I would get a day or two off. If they needed re-shooting, off on another morning excursion. Fortunately, the weather remained cooperative, and I got some nice sequences of the dust and ion tail developments.

Shown here is a wide crop from the morning of 18 March, 1997. It was nearly at it's most spectacular, visible in a dark sky. It was brighter a month or two later, but didn't ever get as far from the sun. Both tails were quite spectacular and well developed. The white tail above is from sunlight reflecting off the dust released by the comet's "dirty snowball" nucleus sublimating as it neared the sun. The bluish ion tail is from the fluorescence of the molecules carbon monoxide and water when sunlight knocks off an electron(CO+ and H2O+). Because these molecules are so much lighter than dust particles, they are driven directly back from the sun from the solar wind. The exposure was 3 minutes on Elite 100 slide film. By the way, I still have the 8" Schmidt camera, but because no one uses film anymore, and the focus of the telescope is inside the light beam it has almost no value at the present time... In this view, north is to the left, west is up.

Earlier this year I blogged about another spectacular comet a few years back. Interestingly, the streakiness in the tail, called synchrones, are visible in both comets. Hale-Bopp set records for brightness. Being very large (estimated 25 miles diameter compared to a "normal" comet's 1-5 miles diameter), it was visible to the naked eye for nearly 18 months (twice as long as the former record holder)! Ironically, the closest it ever got to us was 120 million miles - always on the far side of the solar system. If the comet had appeared 6 months earlier or later when the earth was in that part of it's orbit, Hale Bopp would have been as bright as the full moon!