Please help with these three questions... 3) Why do the Earth and Venus have act
ID: 3163284 • Letter: P
Question
Please help with these three questions...
3) Why do the Earth and Venus have active volcanoes, while Mars and Mercury do not?
4) What evidence tells us that there was once liquid water flowing on the surface of Mars?
5) The Earth and Mars formed at the same time, in the same part of the solar system from similar materials.Yet the Earth is a hospitable place, while the surface of Mars is a cold, frozen desert, with only a very thin atmosphere today.Explain why Mars ended up like this. In other words, what events in the history of the planet Mars caused it to end up like this?
Explanation / Answer
3) Due to lower gravity on Mars and Mercury, the byouant force generated on the magma rising through the crust is less as compared to Earth and Venus. Therefore the magma chamber is deeper down in Mars and Mercury than in Earth and Venus. Therefore in order to reach close to the surface, the magma body has to be large enough in Mars and Mercury. This means that in these two planets eruptions are less frequent and active volcanos are usually not found.
4) Downhill flows, known as recurring slope lineae (RSL) have been detected on the Martian surface, which are usually described as related to the flow of liquid water. Hydrated minerals have also been detected on the slopes. The Pathfinder had found conglomerates on the surface which require liquid water to flow.
5) The answer lies with the greenhouse effect. Unlike on Earth, Mars has no plate tectonic activity that could have recycled carbon dioxide so that it would not have been locked away in the form of carbonates in rocks. Mars has a smaller mass than Earth and hence its internal heat engine gave away quickly enough and its volcanic activity died away long ago. Once its volcanic activity got over and rainfall occured on Mars, carbon dioxide was removed from but not replaced in the Martian atmosphere. Therefore in absence of the greenhouse effect, Mars underwent cooling and turned into a frozen desert.