Source of Mercury's Core

[RalofTyr]

Mercury still has a motlen core and a magnetic field. What is the source of this?

[tusenfem]

Uh, heat?

[G O R T]

The core of Mercury produces heat from radioactive decay just as the Earth.

Perhaps "still" alludes to the idea of the small core of a small planet cooling off more quickly. This would have happened too, if not for the large solar influx reducing the thermal gradient from the core to the surface.

[Kaptain K]

Add in tidal flexure due to Mercury's elliptical orbit very deep in the Sun's gravity well.

[aurora]

And I assume the fact that Mercury has a very large core for the size of the planet.

[korjik]

How about:

When did they start thinking that Mercury has a liquid core?

Has anyone heared any evidence that the core is liquid? If so, what is it?

[korjik]

The core of Mercury produces heat from radioactive decay just as the Earth.

Perhaps "still" alludes to the idea of the small core of a small planet cooling off more quickly. This would have happened too, if not for the large solar influx reducing the thermal gradient from the core to the surface.

The thermal gradient isnt that much different when going from 3000K to 700K as when going from 3000K to 300K. The gradients for Mercury and the Moon should be more dependent on composition than on radiation influx.

[RalofTyr]

Thanks. My reasoning is, since Mercury still has a liquid core and Mars doesn't, what's the difference between the two worlds?

[Noclevername]

Thanks. My reasoning is, since Mercury still has a liquid core and Mars doesn't, what's the difference between the two worlds?

Composition and tidal flux. And Mars' core is speculated to still be semi-molten, not solid.

[aurora]

Thanks. My reasoning is, since Mercury still has a liquid core and Mars doesn't, what's the difference between the two worlds?

Although Mars' magnetic field is a remnant and no longer global in nature, Mars has had volcanic eruptions in the recent geologic past (certainly in the millions of years, rather than billions, since the most recent eruptions).

[Lord Jubjub]

How about:

When did they start thinking that Mercury has a liquid core?

Has anyone heared any evidence that the core is liquid? If so, what is it?

VERY strong magnetic field. Stronger than Mars and, I think, stronger than Venus. Only a molten core could produce such a strong field.

[tusenfem]

VERY strong magnetic field. Stronger than Mars and, I think, stronger than Venus. Only a molten core could produce such a strong field.

well, it is not difficult to have a stronger magnetic field than Mars or Venus, as the two siblings don't have an internal magnetic field, only an induced magnetosphere.

[G O R T]

The thermal gradient isnt that much different when going from 3000K to 700K as when going from 3000K to 300K. The gradients for Mercury and the Moon should be more dependent on composition than on radiation influx.

Crustal composition is important but to a fair degree ubiquitous. The point is that typical igneous and metamorphic crustal materials have a non-linear thermal conductivity which typically transmits 3 to 7 times more (phonon) heat flow at temperatures below some 270K than above 500K-600K.