# How much (in meters) is a black hole's diameter? Where do you go if you were to be sucked down a black hole? What would happen to you?

#### The diameter of a black hole depends on the mass of the original object that becomes a black hole. By the way, before they were called black holes, they were called gravitationally completely collapsed objects.

The basic idea is that the radius of a black hole is that distance from the center where the escape velocity is equal to the speed of light. This is known as the Schwarzschild Radius. It can be calculated from the following equation:R = 2*(GM/c^2)

In this equation, G is the gravitational constant, M is the mass of the original object, and c is the speed of light.

If the Earth became a black hole it would have a diameter of about 0.017 m, about the size of a marble. If the material in the Sun were to become a black hole, the black hole would have a diameter of about 6000 m, a little less than 4 miles.

No one really knows what would happen if you were to get sucked into a black hole. In fact, if our current theories of black holes are correct, no one outside a black hole can know. The issue is that as you pass the edge of the black hole, called the event horizon, no signal transmitted by you can escape from the black hole. Therefore no information from the inside of a black hole has ever been detected by our scientists outside of a black hole.

The most common speculation about what would happen to you if you were to get sucked into a black hole is that due to tidal forces, you would be stretched like a string of spaghetti until you snapped!

Submitted by John (MI, USA)

Submitted by Madalynne (CO, USA)

(October 13, 1997)