Hubble Space Telescope observes Hale-Bopp in October 1995.
Already the brightest object in the morning sky, comet Hale-Bopp is getting brighter by the day and is poised to become the comet of the century -- as in brightest, most impressive, and most useful to scientists.
Still, for all the hoopla, comets are homely objects -- nothing more than dirty snowballs. But when the sun heats them up, they catch the light and produce streaming tails that paint the heavens with light. Granted, this light is best seen in an area with dark skies, but don't we city folks always need an excuse to drive out on a dark country road?
Come to think of it, it's been a boom time for comets. In 1994, Shoemaker-Levy busted apart and machine-gunned Jupiter, leaving a series of wounds in the Jovian atmosphere that took days to heal, and lending credence to the possibility that certain linear patterns of craters on Earth and other planets could be due to other fragments of space junk.
Last spring, comet Hyakutake came whizzing through the solar system, faster than a speeding bullet and much more attractive. This spring, as if to make goggling at comets an annual groove, here comes Hale-Bopp, a monster of a comet that is reported to be 40 kilometers in diameter.
Already, reports Alan Hale, one of the comet's two discoverers, the comet has an 8 degree plasma tail (defined) and a 2 degree dust tail. For reference, the moon covers half a degree of sky, so an 8-degree tail would be a truly awesome sight. And those were early February measurements -- and the stats will surely grow more impressive as the comet nears the sun and stuff really starts to boil off.
But hold your horses -- Hale-Bopp's closest approach to the sun occurs April 1. And if you're still awake, you know that that's April Fool's Day -- a conjunction that should remind scientists that comets are hard to predict. (The thoroughly unstartling appearance of the widely heralded Kahoutek in 1973 taught astronomers to muffle their excited predictions in caution.)
So what's known about Hale-Bopp, and
why should we care about it?
Comet Hale-Bopp hoved into view of telescopes on July 23, 1995. As Alan Hale, one of the comet's discoverers, describes it, he was killing time between observing two known comets by pointing his telescope toward Sagittarius, a constellation that appears near the center of the Milky Way. That's when he saw another "little fuzzball."
Endearing term for a hunk of ice and dust, isn't that?
Since he'd surveyed that region two weeks earlier, Hale was surprised. But he was not the only astronomer seeing a surprising apparition (defined) that night. Over in Arizona, Thomas Bopp was also witnessing the onrushing comet, so, following convention, the comet became their hyphenated namesake.
Comet Hale-Bopp sparked an elated uproar because it was so bright at such a great distance. Bright means big. As best we can determine, the comet's nucleus (defined) is about 40 kilometers in diameter, making it possibly the largest comet known. For comparison, Halley's Comet was about 8 by 16 kilometers, and Hyakutake was a measly 3 kilometers.
So why was Hyakutake so bright? Because it passed within about 10 million miles of Earth, 10 times as close as Hale-Bopp will come. And since brightness falls with the square of the distance, Hyakutake seemed extraordinarily bright, even though it was not intrinsically (defined) bright.
The best estimate is that Hale-Bopp has passed through the solar system at least once before, about 2500 to 3000 years ago, Hale says. The tails he saw are jets of gas and dust that mark its emergence from the deep-freeze of deep space and into the toasty warmth of the sun.
The comet will probably continue to brighten until late March or early April. In March, for northern-hemisphere viewers, the comet will be visible in the northeast sky in the morning and northwest in the evening. Look for a cotton-ball-like blob with various tails coming off. Southern-Hemisphere viewers will have to wait until May to get a good gander of the comet. As always, the best place to look is the darkest place you can find with clear skies, and that means the further from a city, the better. Need further suggestions for viewing Hale-Bopp?
Why should we care about it?
You're starting to repeat yourself ... just another sign of comet fever.
