Using Galaxies as a Telescope
In one of the first tests of Einstein’s theory of general relativity, scientists pointed a telescope at the sun during a solar eclipse. The goal was to measure how much the sun’s gravity deflected the light from stars.
In a manner similar to that experiment, scientists are using massive gravitational bodies in space and their effect on light as an experimental tool, with a side effect of producing beautiful images of the process.
The above link is to the wonderful Astronomy Picture of the Day, and it clearly shows arcs formed by the bending of light over vast distances—approximately 17 sextillion miles away! By studying similar results of gravitational lensing, astronomers are able to measure difficult quantities such as the amount of matter (including dark matter) in galaxies and the distance to some of the furthest objects in the visible universe.
Posted by carneywilson on Jun. 22, 2010