Posted on 06/16/2004 2:30:59 PM PDT by ckilmer
Did comets flood Earth’s oceans?
Did comets flood Earth's oceans?
16 June 2004
Did the Earth form with water locked into its rocks, which then gradually leaked out over millions of years? Or did the occasional impacting comet provide the Earth’s oceans? The Ptolemy experiment on Rosetta may just find out…
The Earth needed a supply of water for its oceans, and the comets are large celestial icebergs - frozen reservoirs of water orbiting the Sun. Did the impact of a number of comets, thousands of millions of years ago, provide the Earth with its supply of water? Finding hard scientific evidence is surprisingly difficult.
Artist's impression of Rosetta orbiter and lander
Ptolemy may just provide the information to understand the source of water on Earth. It is a miniature laboratory designed to analyse the precise types of atoms that make up familiar molecules like water.
Atoms can come in slightly different types, known as isotopes. Each isotope behaves almost identically in a chemical sense but has a slightly different weight because of extra neutrons in its nucleii.
Ian Wright is the principal investigator for Ptolemy, an instrument on Rosetta’s Philae lander. By analysing with Ptolemy the mix of isotopes found in Comet 67P/Churyumov-Gerasimenko, he hopes to say whether comet water is similar to that found in Earth’s oceans. Recent results from the ground-based observation of another comet, called LINEAR, suggested that they probably are the same.
If this is true, then scientists have solved another puzzle. However, if the comets are not responsible for Earth’s oceans, then planetary scientists and geophysicists will have to look elsewhere.
For example, the answer could be closer to home, through processes related to vulcanism. Also, meteorites (chunks of asteroids or comets that fall to Earth) have been found to contain water but it is bound to the minerals and in nothing like the quantity found in comets.
However, since the Earth formed from rocks similar to the asteroids, it is feasible that enough water could have been supplied that way.
If comets did not supply Earth’s oceans then it implies something amazing about the comets themselves. If Ptolemy finds that they are made of extremely different isotopes, it means that they may not have formed in our Solar System at all. Instead, they could be interstellar rovers captured by the Sun’s gravity.
Rosetta, Philae and Ptolemy will either solve one scientific mystery, or open another whole set of new ones.
Europe's comet chaser
• - (http://www.esa.int/SPECIALS/Rosetta/index.html)
More about...
• Rosetta factsheet (http://www.esa.int/esaSC/SEMJUZS1VED_index_0.html)
Related articles
• New destination for Rosetta, Europe's comet chaser (http://www.esa.int/SPECIALS/Rosetta/SEMLSFS1VED_0.html)
• Landing on a cosmic iceberg (http://www.esa.int/esaSC/SEM6N12A6BD_exploring_0.html)
• ANIMATION: Life of a comet (http://www.esa.int/SPECIALS/Rosetta/SEM3NV0PGQD_0.html)
• Asteroids: The discovery of asteroids (http://www.esa.int/esaSC/SEMDVF9YFDD_index_0.html)
Related links
• Arianespace (http://www.arianespace.com)
• Astrium Space (http://www.astrium-space.com/)
• DLR (http://www.dlr.de)
They might, but the lack of atmospheric pressure and gravitational atraction would cause sudden evaporation into space like the primordial atmosphere the moon once owned .
In related news, rain is caused by meteor showers.
>> Wasting European time and money -- it's from ESA.
Oh well in that case, the world needs more studies like this one. *snicker*
Unlike the earth, it doesn't have PMS...
I'm with you on the comet theory. Check this article out...
http://smallcomets.physics.uiowa.edu/blackspot.html
Every few seconds a "snowball" the size of a small house breaks up as it approaches Earth and deposits a large cloud of water vapor in Earth's upper atmosphere.
A million comets is 1 comet every 1000 years for a billion years.
I thought this hypothesis was idiotic, too. But I read a fascinating article a few years ago about it, and was surprised to see that what had been tossed aside decades ago as a silly theory was actually gaining renewed support because of some sort of breakthrough in astronomy that lent some serious credibility to it.
Crude estimates of the brightness of small comets which are devoid of brightly glowing dust particles are indeed about the brightness of Venus, and their impact rate is about 10 million per year. It is remarkable that the orbits and speeds calculated for many of the "fireballs" are similar to those for the small comets.
From here...
http://smallcomets.physics.uiowa.edu/lecture/lect5.html
Dirty snowballs the size of houses, by the millions.
What's the liklihood that comet ice is going to bear any resemblance to water that has been on earth for at least 4000 years and been evaporated and rained and eroded rocks and been filtered through bedrock and drained back into the ocean any number of times?
Well, yes.... but there was already water by the time Noah came around. ;-)
Comets May Be the Source of Earth's Water
http://www.universetoday.com/am/publish/comet_water_source.html?2332006
"Because of their large ice content, comets were leading candidates for many years, but recent analysis of comet water has shown that comet water is significantly different from typical ocean water on Earth. Asteroidal ice may give a better match to Earth's water, but until now, any ice that the asteroids may have once contained was thought to either be long gone or so deeply buried inside large asteroids as to be inaccessible for further analysis. The discovery of main-belt comets means that this ice is not gone and is still accessible (right on the surfaces of at least some objects in the main belt, and at times, even venting into space)."
There is no size limit to a comet :)
A planet the size of jupiter can be a comet if it flies through space unbound by a star. Besides, millions of comes of a period of billions of years is not that much.
Im waiting for discovery of tiny red life forms in the comet ice :)
This topic is from 2004. :')
oops.
But why did you send me a ping from an old thread?
It's related to a topic you'd recently started, or something'.
Thanks!
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