Naked Science Forum

Non Life Sciences => Physics, Astronomy & Cosmology => Topic started by: thedoc on 08/04/2013 10:30:02

Title: Do comets gain mass as they go along?
Post by: thedoc on 08/04/2013 10:30:02
David Gould asked the Naked Scientists:
   
Does a comet like Halley's gain mass as it passes through the Kuiper belt, or will it eventually evaporate?

What do you think?
Title: Re: Do comets gain mass as they go along?
Post by: Pmb on 08/04/2013 14:48:40
David Gould asked the Naked Scientists:
   
Does a comet like Halley's gain mass as it passes through the Kuiper belt, or will it eventually evaporate?

What do you think?
They eventually evaporate.
Title: Re: Do comets gain mass as they go along?
Post by: chris on 08/04/2013 19:41:55
But do they gain any mass along the way? That is, although the net outcome is evaporation or sublimation, do they also gain material during any phase of their lives?
Title: Re: Do comets gain mass as they go along?
Post by: yor_on on 09/04/2013 02:26:57
Yes, If I remember right they are supposed to do so. But can we prove it?
Title: Re: Do comets gain mass as they go along?
Post by: Pmb on 09/04/2013 05:31:10
But do they gain any mass along the way? That is, although the net outcome is evaporation or sublimation, do they also gain material during any phase of their lives?
When far from the sun the outgassing ceases. At that time the comet can gain a tiny amount of mass. But that is quickly lost by out gassing/sublimation. Haley's comment gets smaller and smaller with every passing. E.g.

http://www.uni.edu/morgans/astro/course/Notes/section4/new22.html
Quote
Comet Halley was named after Edmund Halley, who first determined that comets are objects that return to the inner solar system on periodic bases and are therefore predictable. He did not discover the comet that is named after him, but because he "demystified" comets, the comet whose orbit he determined and whose return he predicted is named after him. The comet came by the inner part of the solar system in 1986 and won't come back again until 2061. Its passage in 1986 wasn't very spectacular, and the 2061 trip will probably not be very good either. This comet has gone around the Sun quite a few times, so it has been getting smaller and less spectacular with each passage.
Title: Re: Do comets gain mass as they go along?
Post by: chris on 14/04/2013 11:10:56
So the OP is right to suggest that some mass may be added while the object is in deep space, although this is rapidly offset by degassing secondary to solar radiation energy input when the body returns to the inner solar system.