The Comet of the Century
Did ISON survive its trip around the sun?
Comet ISON is only "mostly dead," maybe.
ISON has been touted as the "Comet of the Century."
"There's great interest in comet ISON for a couple of reasons. First of all, it's coming from the very edge of our solar system so it stills retains the primordial ices from which it formed four-and-a-half billion years ago. It's been traveling from the outer edge of the solar system for about five-and-a-half million years to reach us in the inner solar system, and it's going to make an extremely close approach to the sun and hence could become very bright and possibly a very easy naked-eye object in early December," explains Don Yeomans, manager of NASA's Near-Earth Object Program Office at the Jet Propulsion Laboratory.
So, what happened when ISON approached the Sun on November 28? The comet's fate remains unclear, though astronomers were mostly pessimistic about its survival. Images from NASA/ESA spacecraft SOHO showed ISON approaching the sun, and then nothing came out on the other side. ...until, finally, something did! According to NASA, "The question remains whether it is merely debris from the comet, or if some portion of the comet's nucleus survived, but late-night analysis from scientists with NASA's Comet ISON Observing Campaign suggest that there is at least a small nucleus intact."
Ongoing analysis will reveal more.
We might be able to see the remnants of ISON without telescopes later this month. Whatever's left, "its closest approach to Earth at the end of December, when it will be 60 million kilometers away. A few weeks later, it's possible that we'll pass through the debris trail from ISON, and see some meteors from it," says astronomer and blogger Phil Plait.
Fascinatingly, ISON's suspenseful and unexpected dimming and intensifying will teach scientists a lot. NASA explains,
"Such brightness changes usually occur in response to material boiling off the comet, and different material will do so at different temperatures thus providing clues as to what the comet is made of. Analyzing this pattern will help scientists understand the composition of ISON, which contains material assembled during the very formation of the solar system some 4.5 billion years ago."
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