What is gravity?
Gravity is a type of force that is very strong and that's why jump you always get pulled down and not get pulled up but if your not happy about being on the ground you should because you don't want to be high all day.
Why is gravity strong on earth and not in space?
It's strong on earth because for scientific reason there is very high amount of gravity and space has a very low amount of gravity so the balances are uneven.
What's gravity's purpose?
So you don't go up you want to stay on the ground and if went up you would float to space and don't to go there then you would not breath and you need to breath or you will die.
What if didn't have gravity?
Then everyone would float to space and no one would breath and will die then no one exist anymore then there would be no one left to see.
Why can aircraft fly spacecraft
The aircraft and spacecraft have engines to make them have incredible speeds to make them fly and not get pulled down to the ground and crash.