How long gravity works

Keep up with Union University events on campus and student, faculty and alumni engagement around the world. Site Map Employee Directory. You commonly hear people refer to the weightlessness of the astronauts and zero-gravity. But, are they truly weightless and is gravity zero? The short answer is no , the shuttle astronauts are certainly not weightless as they orbit the Earth, rather only apparently weightless. However, it does weaken as one gets further from the center of the Earth.

The Shuttle orbits about mi above the surface, roughly the distance between Jackson and Nashville! A pound astronaut here on Earth would, in the Space Shuttle, have a weight of 0. This is by no means weightless, so why do we refer to astronauts as being weightless?

But, to answer that we need to use our imagination. Suppose you take a cannon to the top of a high mountain. We normally ignore the curvature of the Earth, but we cannot here. More Curious Kids articles, written by academic experts:. Why do we lose our baby teeth? Our guinea pigs have dark eyes. Why do we have white eyes? How was the Earth made? Portsmouth Climate Festival — Portsmouth, Portsmouth.

Edition: Available editions United Kingdom. Become an author Sign up as a reader Sign in. Gravity helps stars to form. Brooke Simmons , Lancaster University. Category: Space Published: June 9, The attractive force called gravity does not extend beyond galaxy groups.

As you get farther away from a gravitational body such as the sun or the earth i. However, Newton's law of gravity is wrong. The most correct theory of gravity is currently not Newton's law, but is Einstein's General Theory of Relativity with the cosmological constant included. General Relativity describes how gravity is not really a direct, classical force. Rather, the effect we call gravity is simply how objects move in a spacetime that is itself curved.

A mass such as the sun does not shoot out gravitational force field lines. Rather, mass warps space and time, and when an object travels in a straight line through a warped spacetime, the object seems to be acted on by a force. General Relativity does more than explain traditional gravitational attraction.

It also explains other ways in which spacetime behaves. The behavior of spacetime depends on how much mass and energy is present, how it is distributed, and how it is moving. On the scale of groups of galaxies and smaller, there is enough localized mass present to make spacetime act like traditional gravity. In other words, on the scales of ants, waterfalls, humans, planets, solar systems, galaxies, and galaxy groups, spacetime behaves in such a way that one mass seems to gravitationally attract another mass.