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Fraser
2004-Jan-09, 09:58 PM
SUMMARY: Astronomers from the Harvard Center for Astrophysics studied Comet Kudo-Fujikawa as it swept past the Sun in early 2003, and they noticed it was emitting large amounts of carbon and water vapour. This new view of the comet matches observations of other stars that indicate there could be comets emitting similar material. Since other stars probably have comets, it increases the likelihood that they could also have rocky planets, like the Earth.

What do you think about this story? Post your comments below.

DippyHippy
2004-Jan-09, 10:23 PM
Anyone know why it would necessarily mean there would also be rocky planets if there are comets? I'm just wondering why there might be a link between comets and Earth-like planets specifically. Isn't it possible for all types of systems to have comets, but not necessarily Earth-like planets?

om@umr.edu
2004-Jan-10, 05:15 AM
Originally posted by DippyHippy@Jan 9 2004, 10:23 PM
Anyone know why it would necessarily mean there would also be rocky planets if there are comets? I'm just wondering why there might be a link between comets and Earth-like planets specifically. Isn't it possible for all types of systems to have comets, but not necessarily Earth-like planets?
I agree that the astronomers from the Harvard Center for Astrophysicsthere have not shown a link between the presence of rocky, Earth-like planets and comets.

Rocky planets are made mostly of highly evolved nuclear material, i.e., consisting of elements like Fe, Ni, S, Si, made in the deep interior of highly evolved stars. The first ones found outside the solar system were orbiting a pulsar (a spinning neutron star probably made as the collapsed core of a supernova).

Comets, on the other hand, are made mostly of less evolved nuclear material, consisting mostly of light elements, like H, C, N, that are abundant in the outer layers of stars. These are also abundant in the giant, Jovian planets in outer parts of the solar system.

Hopefully the astronomers from the Harvard Center for Astrophysics will tell us why their observation of comets implies the presence rocky, Earth-like planets. It certainly is not obvious.

Oliver :D
om@umr.edu
http://www.umr.edu/~om/
http://www.ballofiron.com/
http://www.chem.umr.edu/web/facres/manuel.html

DippyHippy
2004-Jan-10, 11:44 PM
I've emailed Harvard - we'll see if they reply. I couldn't find the email addies for the scientists themselves but they might still be at the conference where they made the announcement anyway.

DippyHippy
2004-Jan-22, 09:19 PM
I got this reply from one of the Press officers at Harvard...


Dear Richard,

Since comets are essentially icy "rubble" left over from the planet formation process, finding evidence of comets around other stars is a good indirect indicator that those stars may also have one or more planets.

The presence of comets also means that the system contains water. Hence, if
the system happened to possess an Earth-sized world at an appropriate distance
from its star, it might well be Earth-like (i.e. a planet with liquid water).

Sincerely,
Christine

--
Christine Pulliam
(formerly Lafon)
Harvard-Smithsonian Center for Astrophysics

om@umr.edu
2004-Jan-23, 05:29 PM
Originally posted by DippyHippy@Jan 22 2004, 09:19 PM
I got this reply from one of the Press officers at Harvard...


Dear Richard,

Since comets are essentially icy "rubble" left over from the planet formation process, finding evidence of comets around other stars is a good indirect indicator that those stars may also have one or more planets.

The presence of comets also means that the system contains water. Hence, if
the system happened to possess an Earth-sized world at an appropriate distance
from its star, it might well be Earth-like (i.e. a planet with liquid water).

Sincerely,
Christine

--
Christine Pulliam
(formerly Lafon)
Harvard-Smithsonian Center for Astrophysics
Astronomers from the Harvard Center for Astrophysics have still shown no link between the presence of rocky, Earth-like planets and comets.

The surface of the Earth is about 67% water (H2O) and the surface of the Sun is 91% hydrogen (H). However, light weight compounds (like H2O) and light weight elements (like H) accumulate at the surface of planets and stars. But water (H2O) is a minor constituent of the Earth and other terrestrial planets. Hydrogen (H) is less abundant than iron (Fe) inside the Sun.

See <http://www.umr.edu/~om/abstracts2002/soho-gong2002.pdf> or
<http://www.umr.edu/~om/abstracts2002/soho-gong2002.ps>

A link between comets and Earth-like planets might be indicated if comets are observed in the region outside the solar system where rocky, Earth-like planets have been seen, e.g., orbiting the pulsar, PSR1257+12.

With kind regards,

Oliver :D
om@umr.edu
http://www.umr.edu/~om
http://www.ballofiron.com
http://www.chem.umr.edu/web/facres/manuel.html

DippyHippy
2004-Jan-24, 12:57 AM
I wouldn&#39;t have a clue, to be honest&#33; :lol: