Humans have leap-frogged computers by identifying planets outside our solar system that the machines missed. The internet users detected the rocky Earth-like planets in their spare time by scanning the data from the Kepler satellite on the site PlanetHunters.

Astronomers at Yale University have announced the discovery of the first two potential exoplanets discovered by Planet Hunters users in a new study to be published in the Monthly Notices of the Royal Astronomical Society.

It's a big success for the online project which has only been running 10 months since last December, and has 40,000 members.

The site makes use of the one area where humans have a big advantage over computers – pattern recognition.

As Yale astrophysicist Kevin Schawinski puts it "a computer can only look for what you teach it to look for". By contrast, humans, even ones just filling in some time on the internet, are much better at spotting anomalies and unusual features in patterns.

The members of PlanetHunters evaluate different graphs of the light patterns emitted by stars. Dips in brightness can suggest a planet passing over the the face of the star – an occurrence that appears as a trough in a brightness graph. Users flag up odd occurrences for further investigation.

The brightness data is collected by the Kepler satellite – launched by NASA in 2009 to discover planets beyond our own solar system. It has found 1200 candidates for possible planets so far and will follow up on the most promising ones.

Kevin Schawinski described the network of volunteers as a distributed supercomputer: "We've essentially built the world's largest distributed supercomputer, dedicated to pattern recognition. We've linked up over 300,000 human brains and turned it into a science machine."

The two planets picked up by PlanetHunters had initially been discarded by the computers, before the users of the site suggested them for reconsideration.

Yale scientists described the two planets discovered as 2.5 and 8.5 times bigger than the Earth with much shorter orbits – taking only 10 to 50 days to orbit their stars. It is believed one of the planets is a rocky planet like the Earth, though the other may be a gas giant. Neither are believed to be in the so-called "habitable zone" where liquid water – and therefore life as we know it – could exist.

As new data is turned over to PlanetHunters, new discoveries are expected. ®

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