With other words, we might say…what ascends must descend.
This is gravity. Gravity is a force that we are not able to see. Gravity is like a magnet attracting objects back to Earth. When we throw a tennis ball up into the air, the ball comes right back down. When we are hiking and encounter a large hill, we might find hiking quite a bit more difficult. Why? Gravity brings the ball down, gravity makes it harder to walk up an incline. The Earth’s gravity is pulling the ball back down and trying to pull us away from climbing the hill. If we did not have gravity, the ball would continue upward and float away to outer space…and so would we.
Gravity literally pulls everything towards the center of the Earth. When the object is heavier and solid rather than hollow, gravity attracts the object back to earth with a stronger force.
Why do you think that we need gravity besides the fact that we would not want to float away into space? There are two more reasons why we need gravity…
1. Gravity makes certain that the Earth revolves around the sun. Therefore, we can survive on Earth because we are warm and not freezing.
2. Think about what other important property descends to Earth…water that arrives as rain and snow.
So…how do we know so much about gravity? Thank you to Sir Isaac Newton for his discovery of gravity! Newton was a brilliant, eccentric and at times mentally stressed English scientist.
“I have no new ideas for my science book. I’ll be the laughing stock of the scientific community!”
Suddenly an apple fell on his head. He began to wonder, “Why did the apple fall down and not go up?”
Just then, an idea struck Newton. “I’ve got it! Some force must be pulling it down! I’m going to call it GRAVITY.”