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If the earth is round like a ball, why aren't we standing at odd angles around the earth? - Windows to the Universe

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# If the Earth is round like a ball, why aren't we standing at odd angles around it?

#### Well, the fact is, we are all standing at odd angles around the Earth. It just doesn't feel like it because of the force called gravity. Gravity was first "discovered" by Newton. Newton's Law of Gravity says that every body in the universe attracts every other body with a force proportional to the product of their masses and inversely proportional to the square of the distance between them: F=Gm1m2/r2. So, you are pulling on the Earth just as hard as it is pulling on you! However, since your mass is so much smaller than that of the Earth, you do not affect its motion at all. However, the Earth, because of its mass, has a very large pull on you. This pull is what keeps us all from flying off into space. Every object pulls towards its center. If you look at the arrows on the picture, you will see that they all point to the center of the Earth. This is the direction of gravity. Now, when you look at the children, you will see that when they are standing on the surface of the Earth, the force of gravity points away from their feet, into the Earth. Each child, no matter where they are standing, can look "down" and it will be toward the center of the Earth. As you walk along the surface of the Earth, the direction of the force on you is always changing, but it always points to the center of the Earth. If you go visit someone on the opposite side of the world, the gravitational force on you will be in the opposite direction of that which is on your parents, who are still at home. So, we really are standing at odd angles. When astronauts go into outer space, they feel less of a pull from Earth or any other large object. This is why they can float, and there is no "up" or "down."

Submitted by Daniel (Louisiana, USA)
(January 2, 1998)

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Learn about Earth and space science, and have fun while doing it! The games section of our online store includes a climate change card game and the Traveling Nitrogen game!

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Windows to the Universe, a project of the National Earth Science Teachers Association, is sponsored in part is sponsored in part through grants from federal agencies (NASA and NOAA), and partnerships with affiliated organizations, including the American Geophysical Union, the Howard Hughes Medical Institute, the Earth System Information Partnership, the American Meteorological Society, the National Center for Science Education, and TERC. The American Geophysical Union and the American Geosciences Institute are Windows to the Universe Founding Partners. NESTA welcomes new Institutional Affiliates in support of our ongoing programs, as well as collaborations on new projects. Contact NESTA for more information.