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The Chandra X-ray Observatory orbits high above the Earth, peering into the blackest reaches of space.

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Exploring the most menacing and 
magnificent features of the cosmos, this <br>
remarkable telescope is revealing what <br>

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our eyes can't, taking us beyond visible light.

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The bad boys of astronomy, black holes inspire well-deserved wariness and strange fascination.

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But what exactly are they?

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Scientists harnessing the incredible power of Chandra have discovered that black holes 
play a<br>

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critical role in both the development and demise of stars and galaxies.

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While astronomers have long known that 
black holes existed, it wasn't until Chandra <br>
was launched in <br>

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1999 that some of their elusive secrets were revealed.

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With its insightful perspective, Chandra has shed a revealing light on the dark mysteries of black holes.

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Focusing on the deepest depths of space, Chandra has witnessed the gluttonous eating habits of some black holes.

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HARVEY TANANBAUM: And in those 
regions where the X-rays are deficient,<br>

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where the gas voids exist, is the same regions where you see the radio lobes,

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these jets and lobes that are formed from the radios.

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So you know that energetic particles are being shot away from the black hole by some kind of mysterious process,

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and they're clearing the gas away.

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They're pushing the gas aside.

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Because the gas has a density and a temperature, properties that we measure in the X-rays,

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it's very easy to calculate the amount of work that's needed to clear these voids.

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So you can actually measure the energy that's carried out by these jets of particles.

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However, not all black holes mean certain doom for their neighbors.

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Consider the example of one known as Sagittarius A Star, a black hole churning at the center of our own Milky Way galaxy.

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Unlike its more malicious siblings, this black hole appears to be protecting a flock of young stars instead of eating them.

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TANANBAUM: With Chandra, we're able to 
measure the density and temperature of the <br>
gas just outside <br>

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the black hole at the center of the Milky Way galaxy,

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and there's plenty of gas there and it's hot!

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And we should see, even with conservative theories, instead of 100 billion times the amount of radiation that we see,

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we should see a billion times or some 100 million times; it doesn't matter, it's a large factor greater than what we see.

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Equal parts stellar destroyers and cosmic creators, Chandra's black holes exhibit dual nature.

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While some black holes voraciously devour 
gases and galaxies, <br>

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others coddle them, proving yet again that bad boys usually have a good side.

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