[meteorite-list] Fred Whipple and Comet 17P/Holmes - Cannibalizing one's sibling(s)

[David Johnson]

Bernd Wrote:

> "Its appearance was absolutely different from any comet I have ever seen - a perfectly
>  circular and clean cut disk of dense light, almost planetary in outline with a faint,
>  hazy nucleus ... (brightness = Andromeda Nebula)."
>
> By the next night, it brightened perceptibly and he saw an outer faint diffuse envelope
> some 80,000 kilometers in diameter. The comet must have brightened about a hundred times
> within a very few days before discovery. It was ideally placed for observation in the
> northern sky, not far from the frequently observed Andromeda nebula, and should have
> been discovered earlier unless it had been much fainter.
>
> What distinguished P/Holmes besides its unique appearance was its rare variation in brightness.
> It faded very little for nearly a month, its coma growing larger all the time. Then it plummeted
> in brightness by perhaps 200 times. By January 15, 1893, it looked like a faint globular cluster.
> On January 16, observers in Europe were astonished to find that the comet had almost regained
> its original naked-eye brilliance. It then faded quickly and was last seen in 1893 during April.

Interesting - it appears that this comet might be going through a
cycle, since the discovery appearance is strikingly similar to how it
is now, based on the above account.  Hopefully it will remain visible
now for a month, and could we also be in for a resurgence of activity
a few weeks after that?

Based on what I've read here, if there is similar behavior that
occurred then and is re-occurring now, wouldn't this rule out a
collision, even if by a "sibling"?  Obviously no cannibalism occurred,
since it is here once again.  Would orbital dynamics allow for a
"sibling" body to have grazing collisions over such a time frame,
allowing both bodies to remain relatively intact?

Dave Johnson