Using a technique known as
gravitational microlensing, Oklahoma University astrophysicists were able to detect several exoplanets within a quasar
6 billion light-years away called
RX J1131-1231 (depicted in the illustration above, left). Their research shows that the planets range in size from masses as small as the Moon to ones as great as Jupiter.
The idea behind this technique is derived from the Einstein's theory of
general relativity. Since light waves bend when they pass through space warped by a large gravitational presence, a planet passing in front of a star can act as a lens to focus the light, creating a temporary sharp increase in a star’s brightness, and changing the apparent position of the star. Currently, it's the only known way of finding the smallest and most distant planets, thousands of light-years from Earth.
Being able to detect these at all is an incredible testament to the power of microlensing, not to mention that there is now evidence that there are planets in other galaxies.
