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Planet Hunting

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Efforts to discover other earth-like planets is a process known as “planet hunting.” Scientists can decipher patterns in a star’s light dimming and use those patterns to identify planet candidates.
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Photo by Kenny Crookston

Is earth the only planet in space with intelligent life?

Denise Stephens of the Department of Physics and Astronomy spoke about the search for extraterrestrial life with BYU Radio’s Marcus Smith and Julie Rose on The Morning Show on August 18.

“To find life on another planet, or to find a planet that could host life, would probably be the greatest discovery of mankind,” she said.

A habitable planet would need liquid water, an atmosphere, and a magnetosphere. Stephens said that planets can be determined to be in the “habitable zone” according to the Goldilocks theory, which says that a planet needs to be neither too close nor too far away from its star and therefore neither too hot nor too cold.

“The temperature of the star determines how close you have to be to the star in order to have liquid water on your planet,” she said.

Stephens described efforts to discover other earth-like planets in a process known as “planet hunting.”

She explained that planet hunting begins with the transit method, which is best evidenced by the Kepler Mission. The Kepler Mission searched the area of the sky known as the Summer Triangle for four years in space. It monitored more than 100,000 stars for decreases in light.

After years of monitoring, scientists can decipher patterns in a star’s light dimming and identify planet candidates, which pass in front of the star and cause the star’s light to dim. The Kepler Mission found over 4,000 planet candidates.

“If they saw a drop in light that repeated itself periodically, then they would say, ‘Okay, this is a planet candidate; we need to follow this up with earth-based telescopes,’” Stephens said.

She also discussed NASA’s upcoming TESS (Transiting Exoplanet Survey Satellite) Project, which will monitor particularly bright stars for two years to look for small transit planets. Once a planet candidate’s orbiting pattern has been identified, astronomers know when to observe the planet’s star with telescopes to gather more data.

“You hope there are no clouds [and] you get as many friends and astronomers around the world as you can to look at that one star,” Stephens said.

So is there another inhabited planet in space?

“I think there’s life out there,” she said. “Not all stars have planets, but most stars that do have planets have more than one.  We have about 200–400 billion stars in our galaxy. That’s 200–400 billion planets in our galaxy. To think that we are the only planet out of 400 billion that has life, I think would be naïve. . . . There has to be other life out there.”

To listen to the entire episode of The Morning Show on BYU Radio, click here.