OBSERVING A BLACK HOLE
What does WebGR show?
WebGR simulates what an observer would see when flying around in a rocketship, close to a black hole. You can fly around freely, unaffected by gravity, look at the black hole from any angle, and learn about how its powerful gravity bends the path of light rays, thus acting as a gravitational lens. WebGR produces images using calculations based on Einstein’s general theory of relativity (GR).
How can you observe a black hole?
When we speak of `observing’ black holes, we generally mean that we indirectly observe the black hole through its effects on its surroundings. The black hole itself is not directly visible, except through the action of gravitational lensing (light paths bending in the black hole’s powerful gravitational field). The black hole casts a `shadow’ against and distorts the image of, any light-emitting material whose emission passes close to the black hole.