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View from a Black Hole's Edge
Robert Nemiroff (Michigan Technology University)
A black hole is a rip in the fabric of spacetime, a place where anything that enters, including light, can never escape. If a black hole doesn't shine, how can we tell if we're looking at one? Often, black holes have very energetic environments—disks and jets surrounding the point of no return—that shine in X-rays and radio waves. But even if there is no such environment, we can still detect a black hole by the way it warps light around it (if we get close enough).
Video: 441 kB, MPEG
Warping space
According to Einstein's General Theory of Relativity, matter bends space, which in turn causes gravity. (We fall down, not up, because Earth's mass bends space down toward Earth's center.) Black holes are the ultimate manifestation of gravity; they bend space so much that nothing can ever come back once it falls in. Around such a strong gravitational force, space is twisted and distorted causing light to behave in strange ways. This movie gives us an idea of how just how odd the view might be.
What the movie demonstrates
This movie shows what a background sky might look like if you orbit a black hole from just above the event horizon, the imaginary line dividing the inside
of the black hole from the outside.
The gravity of the black hole is so great that it severely distorts the background starlight. Large light bending effects cause the background sky to appear to move in unusual ways as you circle the black hole. The stars opposite the black hole, with respect to the observer's position, appear to approach at very high speeds and are greatly magnified. If we were to move our vantage point closer to the black hole's horizon, the sky would apparently become flat
and concentrate into one point on the opposite side of the black hole.
Gordon Myers
Centaurus A: Feeding a Black Hole
Thomas Goertel (Space Telescope Science Institute)
Video: 4 MB, Quicktime MOV
Centaurus A, also known as NGC 5128, is a galaxy near our own Milky Way. Astronomers have shown that it is in the process of consuming another, smaller galaxy. This interaction appears to be funneling galactic material into a supermassive black hole hidden at the center of Centaurus A. This movie combines observational data with artistic imagination to show what the space near the black hole might look like.
Active galactic nuclei
Using infrared instruments on the Hubble Space Telescope, astronomers have observed a twisted disk of hot gas swept up in the gravitational whirlpool of Centaurus A. The supermassive black hole is hundreds of millions of times more massive than our Sun and has assembled a twisted disk of super-hot gas around it. Like a wheel wobbling around a loose axle, this active galactic nucleus
fires an energetic jet of material into space. This ejected light glows in X-rays and radio waves and is blasted from the black hole in excess of 10 million miles per hour.
What the movie demonstrates
This movie shows what a background sky might look like if you orbit a black hole from just above the event horizon, the imaginary line dividing the inside
of the black hole from the outside.
The gravity of the black hole is so great that it severely distorts the background starlight. Large light bending effects cause the background sky to appear to move in unusual ways as you circle the black hole. The stars opposite the black hole, with respect to the observer's position, appear to approach at very high speeds and are greatly magnified. If we were to move our vantage point closer to the black hole's horizon, the sky would apparently become flat
and concentrate into one point on the opposite side of the black hole.
Gordon Myers
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