Expert: Steve Nelson - 12/20/2007

Question
Hi Steven

It seems that many are questioning the brightening of Comet Holmes. I find it hard to figure how the comet remains after what must have been an immense impact, and that it's not the first time that it has brightened.

I have wondered if Comet Holmes could be a variable, but brightening periodicaly as a glowing, cold plasma.
See: http://www.ipp.mpg.de/ippcms/eng/presse/pi/05_06_pi.html

Please can you tell me if my knowledge is incorrect, or might there be something to this unusual thinking?

Thanks for any consideration, David.

Answer
According to astronomer estimates, it only lost about 1% of its mass:  http://www.johnpratt.com/items/docs/lds/meridian/2007/comet.html

Just because it spread some mass over a huge area doesn't mean that the dense nucleus of the comet had to be totally destroyed.  The thing is, as someone who teaches vacuum technology I can tell you that the vacuum of space is far superior to anything we can generate artificially on Earth in the best research vacuum chambers.  But covering such a large area radically increases the amount of sunlight impacting material which is dramatically more dense (before it spreads out through the vastness of space) than the empty space surrounding it.  Hence, the dramatic increase in brightness.

As to plasma, high-energy particles from the Sun will generate tiny amounts of plasma as they ionize the ejected matter, but relatively insignificant compared to the total matter.  The plasma experiment you refer to is interesting, but the physics is unrelated.  The comet simply destabilized from being cooked by intense sunlight, causing parts to break away and further disintegrate.