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Comet Unexpectedly Brightens a Millionfold
swordgeek writes "Comet 17P/Holmes, a relatively obscure and (until a few days ago) dim object, has suddenly flared to be literally a million times brighter, going from magnitude 18 to 2.8. It is just outside of the constellation Perseus, which puts it high in the sky and ideal for viewing at this time of year. The comet still appears starlike even in binoculars but should grow to several arcminutes across over the next few nights. The comet is now readily visible to the naked eye. This is a completely unexpected once-in-a-lifetime event, so get out your finest optics (even if it's just your eyes) and go comet watching!"
Looking at the last link in the summary I think we ought to be able to see it
Look for Cassiopeia ( a big and fairly obvious W or M in the sky) and track your eyes downward from it. It's going to be just down to the left of the bright star Mirfak in Perseus.
I wonder what the reason for the brightening is? Maybe it hit Voyager.
Well, the only star it's flying near is the big yellow one you see in the daytime. I haven't seen anything about the reason it got brighter, but my guess would be it has an icy core that has been gradually heating internally as it orbited closer to the sun, until suddenly it burst out as steam. If that's the case, maybe it'll get brighter as it gets closer and warmer... or maybe the lid's been taken off the pot and after a day of spewing a ton of stored-up H2O now it'll settle down and get dimmer.
(Like a balloon when something bad happens!)
This is not an eclipse, so you should be able to watch it from the UK, clouds permitting. If you are worried about latitude, you can check the low-cost flights to Spain and come to watch it from here over the weekend. I think you can see Perseus from the UK, anyway.
Actually, Latitude+time-of-year will make a difference.
But given that the UK and US are on the same hemisphere, that shouldn't be a problem, and if it is... Train + Rome...
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Forget Halley's. It was a dissappointment last time anyways. Hale-Bopp and Hyakutake were even more recent (within the last 11 years) and were spectacular.
"People who think they know everything are very annoying to those of us who do."-Mark Twain
Magnitude is a log scale, with brighter objects having lower magnitudes. Like so much in astronomy, the reason is historical: when the first guy (Greek, probably) decided to categorize stars by brightness he said the brightest stars should be first magnitude, the next brightest second, and so on. Because of the nature of the human eye, the scale is logarithmic. Objects brighter than what this guy considered first magnitude thus have a magnitude of less than one, or even less than zero.
The numbers are funny (rather than -1, 0, 1, 2) because they're giving you sample objects so you can get an idea about the range of the scale.
Hope that helped!
This comet orbits between 2.2 and 5.2 AU and it's last closest approach to the Sun was in May, 2007: http://en.wikipedia.org/wiki/17P/Holmes. An AU is the average distance between the Sun and the Earth.
Comet crusts, the dark stuff that is left over after the ice sublimates, are thought to conduct heat slowly. One theory on why we see outbursts as comets move away from the Sun, as this one is doing, is that the warming pulse from the closest approach takes time to sink down to a reservior of carbon monoxide gas which then sublimate internally and blows off fairly large chunks of the comet. Another theory is that the same thermal pulse reaches a reservior of amorphous water ice, which is more common in space than crystalline ice and thus might be present in comets since their formation. When amorphous ice is warmed, it will become crystalline and release energy because the ordered state of crystaline ice is a lower energy state. This can lead to a chain reaction of further crystallization and energy release that could lead to enough warming to cause sublimation in the interior and then do the same kind of thing as in the carbon monoxide scenario.
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Just a few facts to ruin the joke.
-If a comet is heading directly for us, don't worry. If it is heading where we will be by the time it gets there, on the other hand...
-The comet tail is almost not related to its trajectory, but mostly to the direction of the solar wind hitting it, you can approximately draw a line Sun->comet->tail.
So odds are that if we ever have to collide with a comet, we will most likely be idealy placed to see its tail just before the collision.
I'm slightly appalled. /. readers, check my grammar and links, and then click submit. Lo and behold, it gets accepted. Cool!
/. editors: If you're going to actually edit submissions (and why start now, after ignoring fundamental grammatical errors and duplicate stories for a decade?) then get it right!
I write up what I consider to be an interesting story for
Then I read what I supposedly wrote, and find that words have been put in my mouth. Specifically:
"The comet still appears starlike even in binoculars but should grow to several arcminutes across over the next few nights. "
I did NOT write that. I didn't suggest it. The comet does NOT appear starlike in binoculars at all--it's quite a clear extended disk. ONE person quoted in Sky & Telescope believes that it will expand to several arcminutes in size, but that's strictly conjecture.
Furthermore, I didn't use the word "millionfold" in my subject line. That was kdawson again.
"People who do stupid things with hazardous materials often die." -- Jim Davidson on alt.folklore.urban
Just to be clear on something, I never used the word millionfold in my submission. That was kdawson editing my post for his own glory.
Incidentally, the term has been used both ways, and has etymologically distinct roots, so millionfold meaning 'a million times' is valid.
I can't link directly to it, at the sixth entry (-fold) at Miriam Webster's.
Nonetheless, it wasn't my word. Neither was the claim that the comet is 'starlike in binoculars.'
"People who do stupid things with hazardous materials often die." -- Jim Davidson on alt.folklore.urban
Nope. This comet made its closest approach to the sun back in May. It's now moving away from the sun. It also follows a relatively circular orbit compared to most bright comets, so significant changes in brightness are unexpected.
However, there may have been an unusually large pocket of vapor that form some reason burst out at this point (out-gassing), or it might have been hit by a smaller object.