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Comet ISON Survives Perihelion (Barely)
An anonymous reader sends this update from NightSkyInfo:
"Yesterday, when Comet ISON plunged through the solar atmosphere and behind SOHO's coronagraph (the black disk designed to block out the direct light from the Sun), its nucleus dwindled away to nothing and most of the tail simply evaporated. Everyone assumed that the comet completely disintegrated and died a fiery death. However, several hours after perihelion, ISON began to brighten up again. It is now distinctly evident on live images from SOHO, looks like a comet, and continues to brighten as it moves farther away from the Sun."
Experts are unwilling to say precisely how intact the comet is — we'll need more data to make a conclusion about that — but astrophysicist Karl Battams says this is their best guess: 'As comet ISON plunged towards to the Sun, it began to fall apart, losing not giant fragments but at least a lot of reasonably sized chunks. There's evidence of very large dust in the form of that long thin tail we saw in the LASCO C2 images. Then, as ISON plunged through the corona, it continued to fall apart and vaporize, and lost its coma and tail completely just like Lovejoy did in 2011. (We have our theories as to why it didn't show up in the SDO images but that's not our story to tell - the SDO team will do that.) Then, what emerged from the Sun was a small but perhaps somewhat coherent nucleus, that has resumed emitting dust and gas for at least the time being. In essence, the tail is growing back, as Lovejoy's did.' Here's a GIF of the comet rounding the Sun (put together by Emily Lakdawalla).
...then what we have now are clearly leftovers.
Oblig XKCD
Sun: "Don't touch me, I'm hot!" 8-|
ISON: "Gaaaah I can't stop or even slow down a little or change direction on my own!" D:
Sun "Oh no you're trapped in my gravity now! This is gonna hurt!" 8-(
ISON: "AAAAAAAAAH IT BURNS!!! AAAAH HELP! MAKE IT STOP!!!" D8
Sun: "I can't, I wish I could! Oh man are you OK?" :O
ISON: "Owww so much pain...." x_x
"When information is power, privacy is freedom" - Jah-Wren Ryel
Maybe it went back in time. You know, to save some whales.
This one is directly relevant : http://xkcd.com/1297/
But this one is also relevant http://xkcd.com/1295/ given how many news sites mindlessly repeated the news "ISON disintegrated" when it was apparent in SOHO Lascar C3 imagery that that hadn't happened by 5 hours post-perihelion (see this at 2318 UTC)
If ISON can survive its pass through the corona of the Sun, what else is possible?
Will it be possible that Democrats and Republicans work together for the nation?
Will RIAA/MIAA admit that they have been wrong and allow that piracy in fact is not as harmful to the music industry as they have said?
Will sheeple wake up and take charge of their lives?
Will Thanksgiving day shoppers will be calm, patient, and polite?
Will my boss give me a raise?
Yes I know people say "A snowball's chance in Hell", but a snowball just did... So will these now happen?
Did Comet ISON escape from the solar system ? Too soon to tell, but I would bet it has an even chance of being now unbound.
According to the Minor Planet Center, ISON has (had) a pre-perihelion eccentricity = 0.9999947.
At perihelion, ISON was traveling at about 370 km / sec, and (given that eccentricity) was only about 0.7 m / sec below its escape velocity. Even a small nudge (of a few m / sec) "along track" thus could have enabled it to escape from the solar system forever (or bound it even more tightly), and (given the amount of mass it probably lost) it could have been thrusted by many 100's of m / sec. It's highly unlikely the outgassing thrust was purely at right angles to the direction of motion, so I would rate the probably of escape as ~ 50%.
because it didn't have its ice on.
hi!
{"composition":"iron","melting_temp_celcius":,"1538","will_disintegrate":"false"}
The linked gif seems to show the debris "tail" mostly flowing back along the comet's direction of travel, with some off-axis blow evident in the later post-encounter image. I would have expected the "tail" to always be pointing *away* from the sun as it made this fly-by. Derp?
-DC
There are generally two tails - the dust tail (which lies along the orbit path, like bread-crumbs in a fairy tale) and the (plasma) gas tail (which is blown by the solar wind, mostly directly away from the Sun). When you are just past perihelion ( as at the end of the linked-to video above) the dust tail can actually point (more or less) towards the Sun.
Nav system was using meters. Navigator was using feet.
I've fallen off your lawn, and I can't get up.