Polar ice on Mercury

[james_davis_nicoll]

Mercury's north pole has frozen water according to data revealed Thursday by NASA scientists, confirming the long-held suspicion that the very hot planet closest to the Sun has ice lurking in the shade.

Comments

[chrysostom476.livejournal.com]

Larry Niven gets last laugh.

[nebogipfel.livejournal.com]

Me too. My new job is specifically about the IR spectroscopy of
Mercury's surface.

[remus-shepherd.livejournal.com]

But how much of that ice contains He3?

[harvey-rrit.livejournal.com]

It was liquid helium, isotope ratio not given.

(Sorry, I was acting in my capacity as Official Authority on Known Space. It's kind of a reflex.)

[neowolf2.livejournal.com]

It's too bad the liquid helium critters could not exist. No surface of a planet is going to be colder than the temperature of the microwave background radiation, and the vapor pressure of liquid helium at that temperature is still quite high (more than .1 bar.)

(There are some places in the universe that are naturally colder than the microwave background temperature, but they are very rare, and the conditions that cause them to exist wouldn't occur here.)

[james-nicoll.livejournal.com]

"The Coldest Place" dates from 1964, which means the writing of it but not the publication of it predates the discovery that Mercury is not locked into a 1:1 resonance. It would have been roughly simultaneous with the discovery of the CMB.

You know, it wouldn't have been impossible given when Known Space was being put together for it have had Steady State locked in as a core assumption. See, for example, Pohl and Williamson's 1964 novel The Reefs of Space. After the mid-1960s, you pretty much had to be someone like Hoyle or Hogan to go with Steady State.

[james-nicoll.livejournal.com]

Or, sigh, Ken MacLeod. (http://kenmacleod.blogspot.ca/2005/10/big-bag-never-opened-some-time-in.html)

[austin-dern.livejournal.com]

How did I know before reading that he was going to touch on The Big Bang Never Happened and on New Scientist?

[neowolf2.livejournal.com]

For a thorough (if somewhat dated) scientific demolition of tBBNH, see http://www.astro.ucla.edu/~wright/lerner_errors.html

[austin-dern.livejournal.com]

I appreciate your link. Thanks.

[neowolf2.livejournal.com]

Well, even if you ignore the CMB radiation, the energy received by us from starlight would lead to an equilibrium temperature of about 3K(*). This was pointed out by Eddington in 1926.

(*) This is because we're in a galaxy, and so get a lot more starlight than a randomly chosen point in the universe.

Also, if the Earth were a blackbody and received no external energy input, its surface would still have a temperature of 33 K just due to the need to radiate the flow of internal heat. For a body like Mercury this temperature is probably not too much lower, since the rate of radiation from a blackbody goes as the fourth power of absolute temperature.

[ilya187.livejournal.com]

It's too bad the liquid helium critters could not exist. No surface of a planet is going to be colder than the temperature of the microwave background radiation, and the vapor pressure of liquid helium at that temperature is still quite high (more than .1 bar.)

This excludes Mercury, but not larger (and more helium-rich) planets. What's so impossible about 0.1-0.2 bar helium atmosphere, and thus not-evaporating helium critters?

[neowolf2.livejournal.com]

They could not exist where Niven had them, I meant.

Also, if a planet is large enough to retain a helium atmosphere, I think the internal heat flow would be great enough to raise the surface temperature above the boiling point of helium.

[rwpikul.livejournal.com]

Solar wind and photon bombardment causes helium to boil off into interplanetary space. Hydrogen would suffer the same fate except that it tends to form water in the atmosphere and is kept out of the upper atmosphere because it freezes out.

[jeriendhal.livejournal.com]

Ha! That'll shut those Global Warming alarmists up!

[harvey-rrit.livejournal.com]

Good luck with that.