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Mercury May Have Molten Hot Magma at its Core
mattatwork writes "According to ScienceDaily, NASA has come to the conclusion that the planet Mercury may have a molten core after all, based on high-precision planetary radar readings. You may (or may not) remember the Mariner 10 probe making 3 passes by Mercury between March 29th, 1974, September 21st 1974 and March 16, 1975."
You know that Mercury is in tidal lock with the sun? so it only rotates (I think) once every 87 days or so. This slow rotation rate may explain the weakness of the field. Perhaps its high orbital eccentricity (0.2) and proximity to the sun, and the resultant tidal wrenching would explain the liquid mantle?
"Laugh while you can a-monkey boy!" - Dr Emilio Lizardo
mercury has a 3:2 resonance orbit:rotation which could very well explain a very slow fluid core rotation and thus the weak field since eventually the core will sync with the rotation of the outside of the planet.
Sigs are too short to say anything truly profound so read the above post instead.
You're reading it wrong. It is Mercury has quite a strong field compared to Mars or Venus.g netosphere/magsphere_overview.html&edu=high
Heres a short blurb which mentions that Mercury probably has a molten core written in 2003, http://www.windows.ucar.edu/tour/link=/mercury/Ma
https://en.wikipedia.org/wiki/Inverted_totalitarianism
Don't listen to this guy. Mercury is not tidally locked with the sun, but rotates very slowly at about 3 rotations for every 2 revolutions around the sun. And even more, an ocean does not act as any sort of a buffer against gravitational forces from the sun. There's just not a significant enough amount of water even on Earth to do so.
The corrected link to the Wikipedia article: the Mariner 10 probe
Mercury is not tidally locked with the sun, but rotates very slowly at about 3 rotations for every 2 revolutions around the sun.
I forgot my Mercury trivia; they used to think it was locked before they found the 3/2 resonance. Since the resonance is stable, rotational energy is not being affected anymore. But then that means tidal forces are still heating Mercury over a 1400 hour cycle. The heat loss from friction is probably coming out of the orbital energy making the orbit unstable.
And even more, an ocean does not act as any sort of a buffer against gravitational forces from the sun. There's just not a significant enough amount of water even on Earth to do so.
OK, so the water transmits zero torque until there's how much of it then?
Most of the torque being applied to slow the earth down is transmitted at two hydrosphere/lithosphere boundaries: the one between the inner and outer core, and the one between the crust and the oceans. This is because unlike solid rock, fluids are free to slosh around horizontally. The outer core has more mass but the moment arm and surface area are both bigger for the oceanic boundary.