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Aug 21, 2018

What Is a Black Hole?

cygx1_ill.jpg

An artist's drawing a black hole named Cygnus X-1. It formed when a LARGE star caved in. This black hole pulls matter from blue star beside it.

Credits: NASA/CXC/M.Weiss

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An artist's drawing shows the current view of the Milky Way GALAXY. Scientific evidence shows that in the middle of the Milky Way is a supermassive black hole.

Credits: NASA/JPL-Caltech

Black hole Sagittarius A

This image of the center of the Milky Way galaxy was taken by the Chandra X-ray Observatory.

Credits: NASA/CXC/MIT/F.K. Baganoff et al.

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Sagittarius A* is the black hole at the center of the Milky Way galaxy.

Credits: X-ray: NASA/UMass/D.Wang et al., IR: NASA/STScI

This article is part of the NASA Knows! (Grades K-4) series.

A black hole is a place in space where gravity pulls so much that EVEN light can not get out. The gravity is so strong because matter has been squeezed into a tiny space. This can happen when a star is dying.

Because no light can get out, people can't see black holes. They are invisible. Space telescopes with SPECIAL tools can help find black holes. The special tools can see how stars that are very close to black holes act differently than other stars.

How Big Are Black Holes?

Black holes can be big or small.