Friday, January 11, 2008

Double Einstein Ring...

The Hubble telescope has discovered something most unlikely: a double Einstein ring. A single Einstein ring is caused by a pair of galaxies in the same line of sight from Earth, with the gravity of the nearer one causing the light from the further one to bend, much like an ordinary lens – and the result is that the further galaxy looks like a ring to us. This effect is known as “gravitational lensing”. The photo's story:
The double ring captured here is caused by three galaxies all in the same line of sight from Earth (an improbable event all by itself). Gravitational lensing makes a ring from each of the two further galaxies.
Image of gravitational lens system SDSSJ0946+1006 as photographed by Hubble Space Telescope's Advanced Camera for Surveys. The gravitational field of an elliptical galaxy warps the light of two galaxies exactly behind it. The massive foreground galaxy is almost perfectly aligned in the sky with two background galaxies at different distances. The foreground galaxy is 3 billion light-years away, the inner ring and outer ring are comprised of multiple images of two galaxies at a distance of 6 and approximately 11 billion light-years. (Credit: NASA, ESA, and R. Gavazzi and T. Treu of University of California, Santa Barbara)
Solid science delivered by the amazing Hubble telescope, yet another in the amazing series of accomplishments of NASA's largely unheralded robotic space exploration program...

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