The largest mountain in our solar system is not on Earth but on Mars. Olympus Mons is 72,000 feet tall—that’s two and a half times higher than Everest!

And mountains on Earth will never get that tall. Why?

First, we have stronger gravity. About two and a half times that of Mars.

Our mountains form when tectonic plates push together. One plate slides over the other, or the plates crush together in the middle. Both lift material upward.

And they form when volcanoes carry magma from within the Earth, up and out.

And as soon as they form, gravity starts pulling them back down into Earth’s crust. As they sink, their bases can melt, spreading them wider rather than tall.

Another height-limiting factor is erosion by Earth’s plentiful water.

Rain runs down a mountain, which erodes it grain by grain.

Snow freezes into glaciers, which can carve through mountain ranges, pushing rock debris downhill in front of them.

Or, water seeps into cracks and freezes, then breaks off rock in chips or entire slabs—and gravity takes over from there.

Combined, plate tectonics, gravity and water put a limit on Earth’s mountains. The top ten average around 28,000 feet tall.

However, these forces also make Earth’s mountains rise and fall faster than on other planets in the solar system. They may not be as tall, but in my view, their complex stories make them even more interesting.