New worlds discovered, courtesy of US-Israel team

Kepler-47 is the first multi-planet solar system found in a binary star system

Illustrative rendering of a planet with similar dimensions to Earth (Photo credit: Courtest NASA)
Illustrative rendering of a planet with similar dimensions to Earth (Photo credit: Courtest NASA)

If you still think that besides Earth there are seven planets out there, you’re woefully behind the times.

Hundreds of planets beyond the solar system have been discovered, many of them light-years away from our world, thanks to powerful telescopes plying space. This week, a group of scientists, including Tel Aviv University’s Professor Zvi Mazeh, announced that they had found, via NASA’s Kepler spaceship, a pair of planets revolving around a binary star system — the first multiple planet arrangement in such a star system.

Even more important, the planets appear to revolve around their suns along the same plane, in an orderly configuration, much like the planets in our own solar system. And at least one of the planets orbits its suns in 303 days — not too different from our 365-day solar year. That places the planet in what scientists called the “habitable zone,” meaning that the planet is distant enough from its suns — but not too distant — to theoretically have enough atmospheric pressure to maintain liquid water on its surface.

The newly-discovered star system, about 5,000 light-years from earth, was discovered by Mazeh, along with a team of scientists from San Diego State University in California, and was published this week in the journal Science. A presentation on the discovery was made Tuesday at a science conference in Beijing.

Mazeh, along with Professor William Welsh and Professor Jerome Orosz of San Diego State, made the discovery based on observations from the Kepler Space Observatory, which was launched in March 2009 with the purpose of discovering new worlds similar to earth. Kepler orbits the earth in a manner that enables it to observe the center of the Milky Way, taking pictures and recording space data.

The new system, Kepler-47, is the fifth binary solar system discovered by the mission, containing two of the over 700 confirmed exoplanets (planets outside the solar system). Each of those systems has one known planet orbiting them — all of them discovered within the past year — but Kepler-47 is the first binary system with at least two planets in its orbit.

In a binary system, two suns revolve around each other, while the planets in their system revolve around them. Since there are two suns, planets in those systems get plenty of light, said Mazeh; the twilight period, which begins with one of the suns setting and ends when the second one sinks over the horizon, can be lengthy, depending on what time of the year it is, Mazeh said. Ditto for sunrise. The planets were discovered by measuring the increase and decrease of the intensity of the suns, as photographed by Kepler.

While one of the planets, as mentioned, is in the system’s habitable zone, the importance of the discovery is more astronomical than extraterrestrial, said Mazeh; the fact that the Kepler-47 solar system is planar, similar to our own system (that in itself is exceptional, as most planets discovered have erratic, non-planar or disorderly orbits around their suns). That a system so far from our own has a similar arrangement — and perhaps similar origins — to the solar system, is exciting, Mazeh said.

“Every new planet that is discovered lets us understand the way planets are formed, especially in surroundings so different from the ones we are familiar with. It is only through the advanced equipment on Kepler that we were able to see through the depths of space,” he added.

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