Astronomy and Space


What is the difference between zero-gravity and microgravity?

Zero-gravity is the absence of gravity; a condition in which the effects of gravity are not felt; weightlessness. Microgravity is a condition of very low gravity, especially approaching weightlessness. On a spaceship, while in zero- or microgravity, objects would fall freely and float weightlessly. Both terms, however, are technically incorrect. The gravitation in orbit is only slightly less than the gravitation on Earth. A spacecraft and its contents continuously fall toward earth. It is the spacecraft’s immense forward speed that appears to make Earth’s surface curve away as the vehicle falls toward it. The continuous falling seems to eliminate the weight of everything inside the spacecraft. For this reason, the condition is sometimes referred to as weightlessness or zero-gravity.


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