• Question: Is water on every planet? And are volcanos on every planet?

    Asked by rose.h-t to Alice, Christian, Emma, Steve on 18 Mar 2016.
    • Photo: Emma Dean

      Emma Dean answered on 18 Mar 2016:

      Most of the planets in our solar system do not have water on them. We have very recently discovered that Mars has water. Some of Jupiter and Saturn’s moons have water and it looks like Pluto does too.

      Not every planet has volcanoes either. Mars, Venus and again some of Jupiter, Saturn and Neptune’s moons have volcanoes. Not all of them are active though.

    • Photo: Steve Marsden

      Steve Marsden answered on 18 Mar 2016:

      There’s quite a lot of water in the solar system, but it’s not on every planet has water. This may be for a number of reasons. A planet may be too close to the sun, like Mercury. In this case any water would boil, and radiation from the sun would strip the entire atmosphere from the planet.

      This is one of the reasons that it was such a big deal last year when we confirmed that there are small amounts of flowing water on Mars.

      Volcanos are only on planets that have molten cores. On Earth, there is a lot of heat underground from when it first formed. Enough heat to melt rock. This rock can break through the crust forming a volcano.

      Some other planets colder and have completely solid cores, so don’t have volcanoes. Mars used to have a molten core, and had the largest volcano in the solar system. However, because Mars is smaller than Earth, it cooled far quicker. Its core solidified and the volcanoes stopped erupting.