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Why Do Drops of Liquid Form Spheres in Space?

water, gravity, space, spheres, sphere
The tendency for water molecules to stick together causes it to causes spheres in space. (Image credit: NASA.)

Whether water sits in a lake or a glass of water, Earth’s gravity pulls the liquid downward into the shape of the container it’s in.

But in space, gravity’s effects are different. Objects in orbit are indeed affected by gravity, but they are in freefall, moving constantly sideways while falling toward Earth [Learn more ]. This renders them effectively weightless.

Up there, surface tension shapes water into spheres. Magnetic-like molecules on water’s surface cause the surface to behave like an elastic skin. Each molecule is pulled with equal tension by its neighbors.

The tight-knit group forms the smallest possible area — a sphere.

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Corey Binns lives in Northern California and writes about science, health, parenting, and social change. In addition to writing for Live Science, she's contributed to publications including Popular Science, TODAY.com, Scholastic, and the Stanford Social Innovation Review as well as others. She's also produced stories for NPR’s Science Friday and Sundance Channel. She studied biology at Brown University and earned a Master's degree in science journalism from NYU. The Association of Health Care Journalists named her a Centers for Disease Control and Prevention Health Journalism Fellow in 2009. She has chased tornadoes and lived to tell the tale.