Hmmmwanna bet? On these pages are five astronomy misconceptions that are so common they're almost canonical. Is one of these lurking in your brain? I bet at least one is.

Let's find out how much you know that you think you know, but really don't know.

1

There is no gravity in space

We've all seen videos of astronauts floating weightlessly above the Earth, and of course you've heard the expression "zero-g." But that's a misnomer. Gravity gets weaker with distance (in fact, with the square of the distance), but it never falls all the way to zero. In point of fact, gravity goes on essentially forever.

You cannot "escape the bounds of gravity" anymore than you can escape the grasp of the IRS.

Astronauts look like they are experiencing no gravity because they are orbiting the Earth. What they are really feeling is freefall, since they are in reality "falling" around the Earth. In effect, they are falling toward the Earth, but moving sideways enough to continuously miss it. The net result is they follow the curvature of the Earth, always falling but never hitting.

At the typical shuttle orbital height of 250 miles (400 kilometers) off the Earth's surface, the force of gravity is roughly 90 percent what it is here on the surface. Gravity is still very much in control of the shuttle's (and astronauts') motion. Inevitably, when they land, they return to its full effects.

Some things even astronauts cannot escape. They even have to pay their taxes too.

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