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First comet found with ocean-like water


October 7, 2011

The Herschel Space Observatory has recently analyzed the comet Hartley 2, and discovered that ice found on it has the same composition as ocean water (image by NASA)

The Herschel Space Observatory has recently analyzed the comet Hartley 2, and discovered that ice found on it has the same composition as ocean water (image by NASA)

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A recent discovery may add support to the theory that the water on Earth was brought by a rain of comets. Scientists have analyzed the comet Hartley 2, and discovered that ice found on it has the same composition as ocean water. The discovery was made utilizing an orbiting telescope on the Herschel Space Observatory, which can observe organic molecules by reading their far-infrared wavelengths.

"At the time of the Solar System formation there may have been a large reservoir of such comets with the correct ratio that bombarded the earth," says Paul Hartogh of the Max Planck Institute for Solar System Research in Katlenburg-Lindau, Germany.

"Life would not exist on Earth without liquid water, and so the questions of how and when the oceans got here is a fundamental one," added University of Michigan astronomy professor Ted Bergin, "It's a big puzzle and these new findings are an important piece." Bergin is a co-investigator on HiFi, the Heterodyne Instrument for the Infrared on the Hershel Space Observatory.

Hartley 2 comes from the Kuiper Belt, a zone that is found near Pluto at the edge of the solar system, where there are many more comets which we know little about. The source of Earth's water has been disputed for a long time, with previous theories believing that asteroids where the original water carriers. However, this new discovery strengthens the theory that the water present on Earth was most likely transported by comets from the Kuiper Belt.

"The results show that the amount of material out there that could have contributed to Earth's oceans is perhaps larger than we thought," Bergin said.

Source: Nature Journal

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What is Hartogh\'s specialty at the Max Planck Institute? Foolish fiction?

Are we to presume the tiny amount of water that arrived through even an enormous rain of comets then multiplied like amoebas?


Given that the oceans are getting salter I would say it is just a coincidence.


@ Slowburn I assume you have additional info about the observations as a background for your assumption, since this article does not at all describe in which ways the water found on the comet is similarly composed as sea water. I would guess that salt is not a major similarity, and that the salt has mostly accumulated here on Earth. Not at all a contradiction to the theory of water coming from comets. @ Eideard Words like \"foolish\" should be used sparingly, as the tend to backfire. Why on Earth (pun intended) do you think the amount of water/ice in comets and such is \"tiny\". A considerable percentage of the ones exixting now seem to consist mainly of (various types of) ice. Some are almost like small planets. Also remember that even one hit every thousand years amounts to a lot when the time span is counted in billions of years. Also several scientists seem to believe that in the earlier years, there were many more such objects than now, representing remains of the mass that formed this solar system, indicating that hits might have been way more frequent. In the aeons bygone, the majority of the ones most likely to hit some planet have already done that, so now it seems rare, but of course there are many more. I\'m no scientist, but if I wanted to use the word \"foolish\" here, it would be aimed elsewhere than at the theory presented.

Stein Varjord

The USGS estimate of 332.5 million cubic miles of water fell to earth from comets? Certainly a portion of our water did but I find the idea of that much water coming from comet impacts a stretch.

Michael Gene

re; Stein Varjord

I used the example that I am familiar with. But talking about seawater and ignoring the salt content at least borders on lunacy.


For the posters who assume they know what was referred to in the Article, check the referenced Article.

The \'similarity\' to sea water is in the Deuterium to Hydrogen ratios. Salt has nothing to do with it. The deuterium/Hydrogen ratio is dependent on the conditions when the ices formed. We already know that these icy bodies contain amines, cyanogens, and other nucleic acids and amino acids.

The need to bring some mechanism into the supply of water comes from the recently established fact that there was a major collision around 4 Billion Years ago that resulted in the Moon. This collision was great enough to strip away all the water and air from the young Earth. Yet, within two or three Hundred Million Years, the rock evidence shows the presence of large quantities of water. Around two Hundred Million Years after that, there was oxygen in the atmosphere. A sure indication that life was at work.

After the collision that resulted in the Moon, the entire surface of the Earth was as barren as the Moon is today. It was also molten. The oldest rocks are not sedimentary, there was no water to form them. But, there \'soon\' was.

The work reported here is looking where the water could have come from. The water involved in the formation of the Earth would be quite rare. Sunlight started, and the ice was vaporized inside the orbit of Jupiter. Like the Moon and Venus, then, Earth should have been an environment with mostly Carbon Dioxide with small amounts of Nitrogen. Earth then should be much like Venus is today. But, it isn\'t. Also, the oceans have a different ratio of Hydrogen to other isotopes such as Duterium and Tritium to the lava that comes up from inside the Earth.

Yes, the work reported here is important, but it really doesn\'t mean what the Article\'s author and the commentators assume. Please read the referenced Nature Journal article if you want to understand what is being talked about.


re; YetAnotherBob

Of course that assumes that the ratios of isotopes in the volcanic water released today is the same as it was previously.


So where did the water come from? When you find the answer - then you have to answer: \"How did it get there?\" Why do we need to know? How will I benefit? After all is said and done - I think I\'m safe in saying that I\'m glad it is here and it will stay here. It is too bad I cannot say the same for all earths inhabitants!


Didn\'t the water on earth already come from the multitude of ice on it? Wasn\'t the original theory that the earth was encrusted with a huge layer of ice, which soon melted down in the ocean as we know it after the eruption of volcanoes which spawned islands and landmass? If comets really brought sea water to earth, then wouldn\'t comets heading on a collision course be more frequent and more imminent?

Aaron Yang
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