This means it's easier for things to travel higher. Finally, on the Earth, the land floats on giant plates over the molten rock deep in the Earth. We don't believe this happened on Mars. Without the land moving above them, the hot spots can just keep building larger and larger volcanoes. This question was submitted by Dawnamarie at Windham Primary School, Maine.
Stars have a wide range of sizes.
It is 860,000 miles in diameter - over three times the distance of the Moon from the Earth. Of the 'normal' type stars, ones that generate their energy through nuclear reactions in their cores, the smallest stars are about a tenth the diameter of the Sun. These stars are usually very faint. On the other end of the scale are the supergiant stars which can be almost 800 times larger than the Sun. Stars this large are usually very bright.