posted on Feb, 24 2005 @ 06:16 PM
I’ve found another, somewhat different, more involved, explanation, in an article titled “What’s Water Got To Do With It?”, that appeared in
the August 2001 issue of the “Astronomy” magazine:
“SWAS [the Submillimeter Wave Astronomy Satellite, launched by NASA in 1998] has given theorists [this] problem to solve: A lot of interstellar
space looks unexpectedly like the Sahara Desert instead of the Everglades. Decades-old theoretical models say cold interstellar clouds should be wet,
but SWAS doesn’t see the moisture. (…)
“The missing-water problem has prompted [several researchers] to provide an explanation. They believe the water isn’t missing --SWAS simply
can’t see it because it’s frozen onto the surface of tiny dust particles, and frozen water doesn’t emit submillimeter-wavelength photons.
“The icy-dust-grain theory is hard to confirm. (…) Nevertheless, SWAS’s discoveries of unexpectedly dry clouds have elevated [this] theory to
new prominence. That’s great news for planetary scientists, says [So-&-So], ’because there may be a connection between interstellar icy dust
grains and the glass of water you fill up at your faucet’. (…) The icy-dust-grain idea fits perfectly into current thinking about how Earth got
its drinking water --from icy dust grains that formed icy ’planetesimals’ in the vicinity of Jupiter’s current orbit and then fell to Earth.
“Jump back about 5 billion years to when the solar system [didn’t exist yet]. Later, the center of the collapsing [interstellar] cloud reaches a
critical density necessary for fusion of hydrogen into helium, and our sun ignites. (…) the leftovers flatten into a protoplanetary disk. Near the
sun, temperatures are so high that all the water is vaporized and blown out to the so-called ‘ice line’, near the orbit of Jupiter. Here,
temperatures are cold enough for icy dust balls to form.
“Earth coalesced from dry, rocky material in the warmer region inside the ice line. ’The Earth had to have its water delivered’, says [someone
else]. Some planetary scientists argue that comets delivered our oceans, but two findings suggest that they can be responsible for no more than 10
percent of Earth’s water. Detailed examinations of Comets Halley, Hale-Bopp, and Hyakutake show that all three contain nearly identical
concentrations of isotopically heavy (deuterium-containing) water, and that concentration is twice as high in comets as it is on Earth. In addition,
computer simulations strongly suggest that only a tiny fraction of all the solar system’s comets could possibly have hit Earth. For Earth to get
all of its water from comets, their combined mass would have to have been equivalent to 30 Jupiters --and planetary scientists agree that amount is
much too high.
“But there may have been lots of icy planetesimals.
“Early in the solar system’s history, such wet worlds should have formed beyond the ice line from the steady agglomeration of icy dust balls.
Three of Jupiter’s four largest moons (…) have lots of water ice. They most likely were ‘captured’ by Jupiter’s strong gravitational
attraction. But their more numerous siblings were not so lucky: ‘They were gravitationally perturbed and started sailing in toward the sun,’ says
[that ’someone else’]. ’A tiny number of these could have hit Earth and given us all the water we needed.’ The early Earth was most likely
struck by at least one planet-sized body: The moon is thought to be the byproduct of such a collision. Perhaps our oceans are too.”
In other words, no… but yes.
Two of you have wondered here how the water that volcanos bring to the surface reached the depths of the Earth. It simply sank due to the
gravitational attraction. As the same article says: "(...) if Earth had been larger, all of its water might have sunk to the middle and left the