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View Full Version : Are There Oceans on Neptune?



Fraser
2006-Oct-03, 02:58 PM
Smaller and cooler than the gas giants, Neptune and Uranus are classified as ice giants. It's a good name, since they do have large quantities of water ice mixed in with a largely hydrogen and helium atmosphere. There's very little water at the cloud tops, but the percentage of water increases as you descend towards the heavier core. Could there be a layer on Neptune with enough pressure and temperature for liquid water to form into vast oceans? And if not Neptune, what about a Neptune-like planet orbiting another star?

Read the full blog entry (http://www.universetoday.com/2006/10/03/are-there-oceans-on-neptune/)

John Mendenhall
2006-Oct-03, 05:08 PM
What a huge ball of soup!

Fraser
2006-Oct-03, 05:22 PM
Mmmm. Soup.

Dragon Star
2006-Oct-03, 05:37 PM
Great...now I'm hungry...

Rob1ooo1oo
2006-Oct-03, 08:36 PM
hmm, never really thought of this posibility

Grand_Lunar
2006-Oct-03, 09:40 PM
What about Uranus? It's similar to Neptune, but doesn't seem to radiate heat. Might that fit the conditions for an ocean?

This also might be a good cause for a Neptune orbiter.

Blob
2006-Oct-04, 12:59 AM
Even though Neptune abounds with water, no ocean exists beneath its blue-green clouds, say planetary scientists in California. Nevertheless, Neptune may develop an ocean in the far future--after the Sun dies.

Neptune, the eighth planet from the Sun, is named for the god of the sea. The planet is a giant but not a gas giant: whereas the solar system's two gas giants, Jupiter and Saturn, consist mostly of hydrogen and helium, Neptune and its twin Uranus consist mostly of water ice and rock.

Read more (http://kencroswell.com/NeptuneOcean.html)

Lurker
2006-Oct-04, 01:05 AM
no soup.... :eh:

John Mendenhall
2006-Oct-04, 04:43 PM
If there is an internal heat source on the ice giants, there might be enough energy available to support life after the fashion of Earth's undersea hydrothermal vents. I'm with Grand Lunar, we should send orbiters to planet Neptune and planet Uranus. Planet-wide oceans are a frequent science fiction theme, and counting Europa we have three good candidates in the solar system. Pluto and Charon and the other Kuiper belt objects, and other Jupiter and Saturn satellites, might qualify also.

MaDeR
2006-Oct-05, 03:08 PM
Well, not quite. With existing temperature and pressure in future oceans of Neptune, our kind of life is out of question.

Fraser
2006-Oct-05, 03:33 PM
For the oceans to form, both the temperatures and pressures need to synch up. Water boils away at really low pressures. Really hot water needs really high pressures to stop boiling away. The estimates for Neptune would have water hundreds of degrees K. So, I don't think life would stand a chance.

Blob
2006-Oct-05, 04:32 PM
http://en.wikipedia.org/wiki/Black_smoker

BigDon
2006-Oct-05, 04:46 PM
I have a question about this part of the article:


Still, Wiktorowicz and Ingersoll hold out hope for Neptune's distant future. In 7.8 billion years, the Sun will become a white dwarf. As this Earth-sized star fades, Neptune will receive so little sunlight that the planet will cool. This cooling may cause rain to fall from Neptune's clouds, creating an ocean of liquid water that bubbles with hydrogen gas. However, this ocean would exist not on the planet's surface, as seas on Earth do, but up in Neptune's atmosphere.

What would be under this ocean if its not on the surface, dense "air"? Hot steam?

John Mendenhall
2006-Oct-05, 04:50 PM
Good link, Blob, that gets us to 400 Centigrade.

I've seen speculation that if the water doesn't actually boil, bacteria can adapt.

How about life in supercritical fluids? That's a stretch.

Sloane Wiktorowicz
2006-Oct-06, 04:40 PM
Grand Lunar: "What about Uranus? It's similar to Neptune, but doesn't seem to radiate heat. Might that fit the conditions for an ocean? This also might be a good cause for a Neptune orbiter."

From Uranus' non-dipolar magnetic field, it's thought that Uranus' deep interior is not well mixed but "stably stratified." We decided not to deal with Uranus because we assumed a well mixed interior. Uranus is also tipped on its side, which makes it more complicated than Neptune.

We actually consulted an engineer from JPL regarding how an orbiter might prove/disprove an ocean, and we were toying with the idea of sending long-wavelength radio signals into the planet to reflect off a possible ocean. But the ocean would be so far down that a reflected signal may not be strong enough to reach the orbiter. An orbiter would constrain the density profile of the planet much better, however, which would be very helpful!

Big Don: "What would be under this ocean if its not on the surface, dense "air"? Hot steam?"

A "supercritical fluid," which is what happens to water when hotter than about 650 Kelvin. At this point, density of liquid and gas are the same; i.e., you can no longer have a phase transition. So "dense air" and "hot steam" are qualitatively correct.

Grand_Lunar
2006-Oct-06, 05:34 PM
From Uranus' non-dipolar magnetic field, it's thought that Uranus' deep interior is not well mixed but "stably stratified." We decided not to deal with Uranus because we assumed a well mixed interior. Uranus is also tipped on its side, which makes it more complicated than Neptune.


So Uranus is "not soup" either?
From your description, it sounds like "layer cake". Is that about right?



We actually consulted an engineer from JPL regarding how an orbiter might prove/disprove an ocean, and we were toying with the idea of sending long-wavelength radio signals into the planet to reflect off a possible ocean. But the ocean would be so far down that a reflected signal may not be strong enough to reach the orbiter. An orbiter would constrain the density profile of the planet much better, however, which would be very helpful!


A good cause for a Neptune orbiter. :)

Further looks at Triton would be good too. I wonder if it's as active as Io.


A "supercritical fluid," which is what happens to water when hotter than about 650 Kelvin. At this point, density of liquid and gas are the same; i.e., you can no longer have a phase transition. So "dense air" and "hot steam" are qualitatively correct.

I believe I've heard of that type of fluid, concerning the steam cycle.
Would that also be called saturated steam?
IIRC, steam plants in nuclear power plants use that sort of steam. I may be wrong, though. But it is hot.

John Mendenhall
2006-Oct-06, 05:35 PM
So you propose a layer of liquid water ocean on top of a layer of supercritical steam? That gives me a headache. Are you sure this would work? I keep visualizing the water layer falling through the supercritical gas layer. And if it does work, what goes on at the interface? And at the poles? And what is the heat flow rate between the two layers? This sounds like a spherical planetary sized analog of the heat pipes used by crystal growers.