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Ada from Virginia, wants to know...
How strong is the gravity on Mars?

Let me guess. You’re thinking of going to Mars to get away from your little brother or sister, right? I can totally relate.
Mars is hard to get to, but if you went there, you’d find that gravity is less than half (about 38%) of what it is on Earth. And the reason for that is SUPER WEIRD.
Let me explain. First, the gravity on a planet (the force you feel pulling you down) depends on how much STUFF or MASS the planet is made of. The more mass the planet has, the more gravity you feel when you’re near it.
Now, Mars is made of less stuff than Earth. If you had a giant scale, you’d see that Earth has about TEN TIMES more mass than Mars.
But Mars is also smaller than Earth, which means that when you’re standing on it, you’re technically closer to it, which gives its gravity a boost. That’s because gravity also depends on distance. The closer you are to something, the more you feel its gravity.
It’s sort of like when you’re at recess and you see a bunch of kids gathered together. If you see a HUGE crowd of kids, you’ll be attracted to it just because there are a lot of kids there.
But if you see a small crowd of kids, it’s not as interesting, but you’ll check it out anyway because you can get closer to the action.
The same thing happens with Mars. It’s ten times less massive than Earth, but it’s smaller so you can get closer to it.
In all, that makes gravity on Mars about 38% of what it is on Earth. That means that you can jump about one and a half times higher on Mars than on Earth. For most people, that would make them hit the ceiling (assuming they make ceilings the same height on Mars).
But the WEIRD thing is that nobody knows WHY Mars is smaller than Earth. If you line up the planets that are close to the Sun, it looks like Mars should be bigger, but it’s not.
Some scientists think that when the planets were forming (billions of years ago), Jupiter kept swinging around where Mars was forming.
Jupiter is HUGE (so it has a LOT of gravity), which might have pulled on all the rocks near Mars, speeding them up and keeping them from forming around Mars.
Because of that, Mars wouldn’t have gotten as many rocks as Earth or Venus, which may be why it’s smaller.
I guess that means I should be nicer to my little sister. I wouldn’t want her to blame ME for being so short!

- Oliver

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