The search for earth-like planets: A planet that orbits two stars

Boonsri Dickinson visits Geoff Marcy’s lab at the University of California at Berkeley to hunt for Earth-like planets. Using the Keck telescope in Hawaii and data from the Kepler telescope, Marcy can detect planets millions of miles away.
Written by Boonsri Dickinson, Contributing Editor

For most of his career, Geoff Marcy never thought he'd find any extrasolar planets. But that's all changed.

Marcy is one of the lead astronomers sifting through the Kepler data, and has been credited with discovering 1,700 potential planets that exist outside of our solar system. About 200 of these planet "candidates" were later verified to be actual planets.

With the help of the Kepler and a remote telescope in Hawaii, Marcy is able to see signs of planets orbiting stars millions of miles away, ultimately getting us closer for the search for extraterrestrial life.

Earlier this month, I visited Marcy’s lab. It is pretty standard: computers, a refrigerator, and a couch. But it’s all he needs to scan the heavens for other planets, one or more of which may one day be proven to contain life.

Marcy uses the Kepler spaceborn telescope to detect planets that cross in front of their star. When planets orbit places it between its star and earth, the star dims slightly. Kepler can detect that dimming.

In the lab, I saw Marcy verifying and measuring masses of the planets using the Keck telescope in Hawaii. It's considered best telescope on Earth, with a mirror about 30 feet in diameter.

"I've worked 14 hour days since the 1980's to develop the unprecedented Doppler technique we use to find planets. I started from scratch, with no real hope of finding any planets. I work pretty hard, and I appreciate beauty,” Marcy said. “It’s been a wonderful privilege and a lucky ride because we never thought we’d find any planets.”

Star Wars-like planet

NASA scientists today announced a new planet called Kepler-16b that orbits two stars, a discovery that seems to bring to life the fictional Luke Skywalker home of Tatooine with its double sunset.

The system spotted by NASA consists of one star orbiting another, with the planet Kepler-16b circling both stars. Unlike the barren and rocky Tatooine from the Star Wars films, NASA believes Kepler-16b to be cold and gaseous.

The unique find was discovered in a cache of data recently acquired from NASA's $600 million Kepler mission, the centerpiece of which is a telescope traveling through space 40 million miles from Earth.

There are many planet candidates, so Marcy uses the Keck telescope in Hawaii to verify their existence. By measuring the Doppler effect of the star, they can see wobbling around in a circle, due to the planet yanking gravitationally on its parent star.

More extrasolar planets

This week, Marcy and his colleagues announced they had found another 500 planet candidates. In addition, a Swiss team announced another 50 planets, bringing the total number of potential planets around other stars to about 2,500. Of the new batch, the Tattooine-like Kepler-16b has been verified to be an actual planet.

"We have over 250 stars containing multiple planets," Marcy told SmartPlanet from Jackson Hole.

The only way to see planets millions of miles away is to measure them indirectly. They are otherwise too faint to detect when compared to their brightly shinning host star. A key to detecting the existence of a planet is a 60-inch telescope in Arizona that essentially triangulates data with Kepler.

The search for extraterrestrial life

Searching for Earth-like planets touches on a deeper question: Are we alone in the universe? While life outside Earth has yet to be discovered. Locating planets that are likely candidates is a necessary first step.

“Essentially this new discovery opens up a vast amount of real estate where we might not have thought to look before," Kepler collaborator Lucianne Walkowicz said Thursday. "We know that many stars are not lonely singles but live instead in systems of multiple stars. Since we now have unambiguously detected a planet around a double star system, we know we may be able to find more.”

While this planet is more like the gaseous Saturn, the fact that it’s there means there’s a good chance earth-sized planets may also exist in systems like Kepler 16b. Our understanding of how planets form tells us that Saturn-like worlds probably have rocky centers. While, Saturn-like planets are far from habitable, they’re essentially made of the same ingredients as earth-sized planets.

This post was originally published on Smartplanet.com

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