Space enthusiasts have got one up on professional astronomers by finding a planet in an alien solar system that has four suns. Two volunteers in the USA spotted tiny fades that had previously gone unnoticed in starlight data collected by NASA’s Kepler space telescope. 

The newly discovered planet is depicted in this artist’s rendition transiting the larger of the two eclipsing stars it orbits. Off in the distance, well beyond the planet orbit, resides a second pair of stars bound to the planetary system. Image Credit: Haven Giguere/Yale.

When a giant observatory on Hawaii was used to take a closer look, it found the fades were caused by a planet orbiting a pair of stars. But amazingly, another two stars were going round them.

More than 840 so-called exoplanets have so far been discovered around other stars in our galaxy, suggesting that the true number could run into many millions of not billions. But only seven have been found in double-star systems and this is the first in a system with several stars.

The new planet is thought to be a gas world that is slightly bigger than Neptune and more than six times the size of the Earth. It lies a little under 5,000 light-years away in the constellation of Cygnus and astronomers are puzzled as to how it has kept stable enough to avoid being torn apart.

Kepler has spent the past three and a half years staring at around 160,000 stars in this one small region of the Milky Way looking for fades in any star’s light that indicate planets passing in front of them. It has been an amazing success, finding thousands of candidates for planets that are waiting to be confirmed.

Many of these planets stand out clearly in the telescope data. But the strange new find was made thanks to a website called Planethunters.org that is a citizen science project.

Volunteer enthusiasts scour the data to see if they can identify fades in starlight that have not already been spotted. The new discovery, made independently by Kian Jek of San Francisco and Robert Gagliano from Cottonwood, Arizona, has been dubbed PH1 after the name of the project.

It is one of a number run under the Zooniverse label that include classifying galaxies, studying explosions on the Sun and analysing the surface of the Moon – all instances where the human brain is more suitable than a computer in solving a task.

A paper about the mysterious new planet, which was confirmed by the Keck telescopes on Hawaii, was being presented today by Meg Schwamb of Yale University at the Division for Planetary Sciences annual meeting in Reno, Nevada.

Dr Chris Lintott, of Oxford University in the UK, helped set up Zooniverse and is part of the Planethunters.org team. Chris, who also co-presents the BBC’s The Sky At Night with Sir Patrick Moore, told Skymania today: “The discovery of PH1 is a real triumph for citizen science – Kian and Robert along with the thousands of other volunteers at Planet Hunters have managed to make a remarkable discovery that will have professional astronomers scratching their heads for years.”

Kian Jek commented: “It still continues to astonish me how we can detect, let alone glean so much information, about another planet thousands of light years away just by studying the light from its parent star.”

And Robert Gagliano said: “It’s a great honour to be a Planet Hunter, citizen scientist, and work hand in hand with professional astronomers, making a real contribution to science.”