Planet hunters discover circumbinary exoplanet. Wait, what is that?

NASA's planet-hunting mission Kepler, has detected a new two-star exoplanet – Kepler-453b – orbiting a pair of stars in an area in which life could potentially exist.

Illustration copyright Mark Garlick,
This is an artist's impression of the Kepler-453 system showing the newly discovered planet on the right and the eclipsing binary stars on the left.

Astronomers have discovered a rare exoplanet that orbits not one but two stars. Kepler-453b, as it's been dubbed, is only the 10th circumbinary exoplanet ever discovered.

The newfound planet takes 240.5 days to circle its parent stars, which orbit each other every 27.3 days.

Potentially more exciting, is the fact that Kepler-453b is located within the so-called habitable zone, the area around the stars that is neither too hot nor too cold to support life. And the somewhat unexpected nature of its discovery suggests there could be more like it than previously believed, according to Stephen Kane, an assistant professor of physics and astronomy at San Francisco State University and member of the team that made the discovery.

"If we had observed this planet earlier or later than we did, we would have seen nothing and assumed there was no planet there," Mr. Kane said in a press release. "That suggests that there are a lot more of these kinds of planets than we are thinking, and we're just looking at the wrong time."

Kepler-453b is six times larger than Earth and according to researchers, its size indicates it a gas giant, rather than a rocky planet, and thus unable to have life despite being in the habitable zone. "But it could have moons that are rocky, which means you could have life on the moons in this system," Kane said.

Exoplanets are planets outside of the solar system and were first discovered in the early 1990’s. They are also referred to as extrasolar planets.

In the past two decades, astronomers have identified more than 1a hundred exoplanets comparable in mass to Jupiter and Neptune. Last month, in an unprecedented discovery, NASA announced the finding of the “Earth twin” – Kepler 452b – an exoplanet, that resembles the Earth in age and size.

According to Nasa, "a thorough understanding of exoplanets will tell us much about how our solar system formed, why it has small, rocky planets near the Sun, why it has gas giant planets far from the Sun, why the Earth has the conditions and chemicals that can support life, and why conditions on other planets are hostile to life." 

Kepler, NASA’s first exoplanet mission, was launched in 2009 and has been pushing for search for habitable worlds close to our own solar system. The first two-star system was discovered by the Kepler Mission in 2011.

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