Is it known if Mercury was ever volcanically active because of tidal forces caused by the Sun?

Question

The tidal effects that Jupiter has on Io made me wonder if the Sun ever had the same effect on Mercury. Now I understand that the distances are vastly different and there are great differences in the relationships of these bodies so it might be like comparing apples to oranges. Any help is appreciated.

Answer 1

Like so many other things, the answer is yes and no.

Mercury is supposed to be, size for size, the densest of the planets. It must contain amazing amounts of metals. Because of its density, the solar tides will surely have some effect on it. Metals have properties like ductility and malleability, so that they are accustomed to deforming. I expect that the interior of Mercury will be kneaded by the tidal force of the Sun until it is comfortably molten.

But given that the surface of Mercury is so hot, it lacks one of the fearures Earth has, which allows for volcanoes-- if the pressure of molten material builds up under the surface on Mercury, it will simply ooze out through the (already softened) surface. There will be no eruption leading to a build-up of material in a cone shape.

So there could probably be lava/ molten metal flows, but not 'volcanoes'.

6 NOV 06, 1840 hrs, GMT.

Answer 2

Well, first off it's the tidal force from Jupiter *and* an orbital resonance with the other Galilean moons that makes Io so active.

Today Mercury is totally solid, as far as we know. But it did have a molten interior at one time. In the past, lava did flow on Mercury and cover up some of the early craters, but that was a long time ago. We do notice that there are some "plains" on Mercury that are not as heavily cratered as other areas. But the lava flows happened very long ago. I don't know if the Sun's tidal force helped to keep the interior of Mercury molten for any length of time, though. It certainly doesn't now.

Answer 3

According to a 1971 astronomy book it says that is was NOT volcanically active.