Huge Planet with 31-Hour Year Discovered Around Distant Star

The most recently discovered exoplanet is a true giant, being only six times smaller than the star it orbits. It's located in the constellation Hercules about 10 degrees west of Vega, the brightest star in the summer skies and was discovered by an international team of astronomers with the help of a network of small automated telescopes in Arizona, California and the Canary Islands.

"TrES-3 is an unusual planet as it orbits its parent star in just 31 hours!," said Georgi Mandushev, Lowell Observatory astronomer. "That is to say, the year on this planet lasts less than one and a third days. It is also a very massive planet - about twice the mass of the solar system's biggest planet, Jupiter - and is one of the planets with the shortest known periods."

Named TrEs-3, the gas giant is similar to our own Jupiter but about 30 percent bigger and about twice as massive. It was discovered due to the fact that it's a transiting planet, meaning that it passes in front of its star. It has a short orbit around a star slightly smaller and cooler than the Sun, located at about 800 light-years and because of that, it's also very hot, around 1,500 degrees Kelvin.

"TrES-3 will be an intriguing object to study more deeply, said Edward Dunham, Lowell Observatory instrument scientist. "For example, its tight orbit causes it to be illuminated very strongly. This may make it possible to measure the variation in reflected light as it goes through its phases. This will tell us how reflective its atmosphere is."

Astronomers can't just look for planets in the space beyond our solar system, because they are outshined by the stars they orbit, so actually looking for them is like searching for a firefly next to a lighthouse. The fact that it passes in front of its star makes it visible, due to the fact that is causes a slight dimming of the star's light in a manner similar to that caused when the moon passes between the Sun and Earth during a solar eclipse.