The extra-solar planet is one of a mere handful detected using a novel technique called microlensing.

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Microlensing occurs when a massive object in space, like a star, crosses in front of another star shining in the background.

BBC: Artist's concept of a distant world (BBC)

The brightness and duration of a microlensing event do depend on how heavy the lens is--the information the team is looking for.

ECONOMIST: The dark side of cosmology | The

To estimate the number of alien worlds, Dr. Cassan and his colleagues studied 100 million stars between 3, 000 and 25, 000 light-years from Earth with gravitational microlensing.

WSJ: Galaxy Hosts 100 Billion Planets, in New Estimate

Using gravitational microlensing, scientists are able to determine when the gravity of a large object alters the light coming from a star on its way to Earth.

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