Is the Earth the only planet that still has melted lava in its core? Why did the other planets cool off?

Question

faster?

Answer 1

Mercury has a molten core (see link below).

So does Mars (see second link).  Heck, Mars has the largest volcano in the solar system (Olympus Mons which is about 3x bigger than Mt. Everest on earth).

As does Venus.

And of course we know the earth does.

That pretty much takes care of all the rocky planets (the rest are gas giants).

Answer 2

Venus also has a molten core.  It's similar in size to the Earth but has a much thicker crust, so there's no plate tectonics.  The molten state is maintained, in both the case of Venus and Earth, by the heat generated in the core by radioactive elements.

Answer 3

No, Venus has a molten core as well. It's a little bigger than Earth, so you can expect Earth's core to cool sooner than Venus.

Mars, for example, is roughly half the size of earth. So, given the size estimate, Mars lost it's molton core way before humans existed.

Unfortunately, the core stopped spining and gave way to ultra-violent rays that scorched the martian surface; no moving core, no electromagnetic field to shield unwanted solar rays.

Answer 4

The other planets are cooler (except Mercury and Venus) as they are away from the Sun. Thus, they do not receive enough heat.

However: Saturn, Jupiter, Uranus, Neptune all have a core consisting of Hydrogen, Helium, Methane and other gases. So, even if it were hotter, there would still not be any "lava".

Answer 5

There orbit is too far from the sun. We have perma frost near the poles.