[Nathan Zachary]

Sure they did. Whenever I hear "scientists say", 99.9% of the time it turns out to be B.S. It's just a "give us more taxpayers money so we can spend our lives slurping at the public trough" carrot the dangle to keep the cash flowing.

A black hole wouldn't be seen gulping a star, the light wouldn't be able to escape the gravity, so the (B.S.) theory goes. More likely, it was just a star that burned out a billion years ago (so the B.S. theory goes) and the light finally stopped reaching earth.

Her's a much better theory- there is a speck of dust on the lens.

[Pox]

You are correct, the light cannot escape the gravity. However, the matter that is circling the Black hole just outside the event horizon is moving at typically millions of miles per hour, and that matter is heated up from such a velocity, and when matter gets that hot, it emits radiation in different varieties, typically x-rays. UV radiation was emitted from the stars matter that was being swallowed just prior to it passing the point of no return, and that 'signature' is the marker we use to detect Black Holes. According to our current knowledge, a Black Hole devouring a star is the only known mechanism to create such a flash of UV radiation.

[Conan the Librarian]

You are right that you wouldn't see the actual star go in, but, you can see the effects of the gravity on the star BEFORE it goes in. Until the ingoing matter crosses the event horizon, the gravitation effects would be pulling and tugging on the star, stretching it like a strand of spaghetti. Besides that, the gravity would also slow down the light coming from the area, thus shifting the light into the red end of the spectrum.

Then, as the matter from the star does cross the event horizon, the gravity differences from one side of the star, and even one side of individual atoms, rips the star or atom apart, releasing enormous amounts of energy, some of which goes toward the black hole, some of which goes out into the universe.

Black holes aren't like what they show in the movies. If the Sun became a black hole all of a sudden, gravitationally we wouldn't notice, as the gravity wouldn't change. It's not like a giant vacuum cleaner.