Poor Comet Elenin is breaking up.
It
was supposed to swing within 22 million miles of Earth, be visible to
the naked eye, and bathe the planet it its tail next month. Alas, a
breakup seems to have started a few weeks ago (whilst the East Coast was
cloaked in hurricane Irene).
I figured we'd have to wait to get a good look at the thing (as it swings into SOHO's field of view sometime this week). But some curious footage has appeared on the intertoobs. It purports (and does appear) to show Elenin's breakup and deflection from a space-borne shockwave of some sort.
Did NASA's STEREO observers indeed provide us with a peek at something? On his own blog, Leonid Elenin mentions the breakup of his comet, but seems unaware of this STEREO footage. Perhaps the object in the STEREO footage is not actually Comet Elenin at all.
My
understanding is that comets are relatively loose collections of ice,
dirt and rock and may start breaking up as they approach the sun, warm
up and start venting. Or from gravitational forces (like the
Shoemaker-Levy coment that hit Jupiter some time back).
According
to Leonid Elenin, the pieces of his comet are now stretching out along
it's path of travel (just as Shoemaker-Levy did). Clearly, though, the
object of attention in the STEREO video is deflected from its course by
some sort of shockwave.
It should be interesting to follow Elenin's fate -but- It all begs the question: What the heck caused that shockwave?
I would sure like to hear Phil Plait's take on this.
[UPDATE: I downloaded the raw images from STEREO's H1B rear camera and made my own animation of the event. Upon review, I've decided that the "shockwave" is not a shockwave at all (but an optical effect) -and- the object in question (if it is Elenin) does not, in fact break up at all -but- continues along it's path (though intersecting with the light from another body and at the precise moment hit by the edge of an optical effect -- which I think might just be a lense-flarey kinda thing that's happening as Jupiter, the bright object to the far right, escapes the STEREO camera's field of view). So there.]
