What Is Earth Gravity?
QUICK ANSWER
Earth gravity is the force that attracts objects toward the center of the planet, with an acceleration of approximately 9.8 meters per second squared at the surface. This force keeps the atmosphere, oceans, and everything else bound to Earth and gives objects their weight.
Earth gravity is the most consistent force in human experience. It pulls equally on a dropped pencil, a falling raindrop, and your morning coffee cup. The exact value, 9.8 meters per second squared, shows up in physics problems from middle school to spacecraft engineering. It varies slightly by location and altitude, but the basic pull defines how everything on the surface behaves.
How strong is Earth's gravity?
Earth's gravitational acceleration averages 9.80665 m/s² at sea level, which is the internationally agreed standard value. This means a falling object speeds up by about 9.8 m/s every second it falls, ignoring air resistance. The actual strength varies slightly across the planet because Earth is not a perfect sphere and density differs in different regions. Gravity is slightly weaker at the equator (about 9.78 m/s²) than at the poles (about 9.83 m/s²) due to Earth's rotation and equatorial bulge.
Why does Earth have gravity?
All objects with mass exert gravitational pull on other objects. Earth has gravity because it has mass, roughly 5.97 × 10²⁴ kilograms. The amount of gravity a planet generates at its surface depends on both its mass and its radius. A more massive planet pulls harder, while a planet with the same mass but a larger radius would have weaker surface gravity because the surface is farther from the center of mass. Earth's particular combination produces the 9.8 m/s² we experience.
How does gravity decrease with altitude?
Gravity weakens with distance from Earth's center according to the inverse square law: doubling the distance reduces the force to one quarter. At the top of Mount Everest, gravity is about 0.3 percent weaker than at sea level. On the International Space Station, roughly 400 km up, gravity is still about 89 percent as strong as on the surface. Astronauts feel weightless not because gravity is gone but because they are constantly falling around Earth in orbit, which produces the same sensation as falling in an elevator. More on how gravity affects astronauts in orbit from NASA's overview of ISS gravity.
What would happen if Earth lost gravity?
Without gravity, Earth's atmosphere would drift away into space within hours, leaving nothing to breathe. Oceans would float off the surface in droplets. Earth itself would gradually fly apart because gravity is what holds the planet together against its own rotation and internal pressure. Even a temporary reduction in gravity would have catastrophic effects on weather, ocean tides, and the structural integrity of every living organism, all of which evolved under exactly this gravitational pull.
Earth gravity at 9.8 m/s² is one of the most reliable forces in human life. It shapes how everything from raindrops to rockets behaves at the surface. The number is small enough that humans can walk and jump against it, but big enough that without it, the planet itself would not hold together.
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