• December 1, 2005

    Episode 12: Einstein Rings

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    Every day, we experience the friendly embrace of gravity. The force of mutual attraction keeps the planets in orbit around the Sun, attaches us firmly to the Earth, and annoys us when we drop something on the floor. But gravity has some other interesting properties. According to Einstein's theory of general relativity, massive objects warp space and time. The force of gravity can cause light to bend toward an object like a giant galaxy. We can watch this happen in an effect called "gravitational lensing," when the gravity of a massive object, like a galaxy, warps and magnifies the images of more distant objects -- much like a giant lens in space. Scientists have found quite a few of these lenses using the Sloan Digital Sky Survey and the Hubble Space Telescope. In fact, 19 new "gravitationally lensed" galaxies have been added to the list of 100 already known. Eight of the objects are so-called "Einstein rings" - beautiful rings produced when two galaxies are almost perfectly aligned.