A viewer of the UK’s Stargazing Live show has helped discover a planet.

Chris Holmes didn’t notice the planet on his TV set (high definition only goes so far) but rather at Planethunters.org, a site that asks volunteers to search through imagery from the Kepler telescope operated by NASA.

Holmes was inspired to check out the site when watching a report on it on the BBC2 show hosted by Professor Brian Cox and comedian Dara O Briain (pictured). The three-episode series of live astronomy broadcast from the Jodrell Bank Observatory tied in with a series of nationwide events.

Visitors to the Planethunters site are asked to look at charts of light measured by Kepler as it observes various stars. A dip in the light level may suggest a planet has passed in front of a star, and multiple observations can give an indication of its size and position.

While computer systems can keep track of and analyse data from the telescope, they work much better for planets in close orbit to stars where there’s a strong pattern. With planets in wider orbit that pass “in front” of the star less frequently, it’s harder for computers to spot what are literally blips. By displaying the data in graphical form, the project can take advantage of the skills humans use in recognizing faces.

In the space of 48 hours during the run of Stargazing Live broadcasters, visitors to the site checked through more than a million images. Among those was one viewed by Holmes, who saw a light dip that appeared to be from a planet passing the orange dwarf star SPH10066540. His observation allowed researchers to look back through the dataset and find several other instances. However, it will take several more observations before the planet’s existence can be formally confirmed.

Based on the available data, researchers believe the planet is around the size of Neptune, but orbits at a similar distance to its star as Mercury does to the Sun.