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Monday, July 27, 2009

Is There Gravity in Space? (Short Answer: Yes)

"Is There Gravity in Space?"
Space.com (July 27, 2009)

"Astronauts and space tourists may rhapsodize about feeling weightless during spaceflight, but don't be fooled by the somewhat misleading term 'zero-gravity.' Every object in space still feels the gravitational pull from other objects, including space travelers who imagine themselves free of Earth's gravitational shackles.

"Earth's gravity affects everything at or near the planet's surface. We feel the force of gravity on Earth through our mass, and that force also translates into a downward pull of 9.8 meters per second squared (32 ft/s^2)...."

Actually, any "space travelers who imagine themselves free of Earth's gravitational shackles" weren't paying attention during their high school physics classes.

This Space.com article is a pretty good overview of the physics of gravity, and gives some interesting factoids along the way: like Earth's gravity in the ISS's orbit being about 90% of what we experience here on the surface.

The term 'free fall' is more accurate than 'weightlessness' - the article explains that something in Earth orbit is falling towards Earth, but that Earth's surface curves away as the object falls. (The trick to staying in orbit is to be moving forward fast enough to keep from hitting the atmosphere.)

A pretty good basic-science article.

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