Kawaler and Kepler have changed what we know about the stars…and new planets

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They’re not searching for E.T., just E.T.’s home.

That’s what Iowa State’s Steve Kawaler said, quoting a colleague, about NASA’s Kepler Mission. He spoke to about 30 Liberal Arts and Sciences alumni and others on May 16 during the university’s Alumni Days.


Kawaler, professor in the Department of Physics and Astronomy, is one of the leaders of the Kepler Asteroseismic Investigation team. Kepler was launched in March 2009. The spacecraft, which he said is “roughly the size of my Suburu Forester,” is orbiting the sun carrying a high-tech light meter to measure changes in star brightness. It has a telescope 37 inches in diameter hooked to a 95-megapixel camera.

Kepler is studying stars and, as a result, is detecting planets in batches, not one at a time. The results of the mission have been “just overwhelming,” said Kawaler. Prior to Kepler, he said there were 300 known planets outside our solar system. The spacecraft now has found about 1,000 known planetary systems, and they’re working on another 4,000.

“We’ve been watching 170,000 stars continuously for four years,” he said, “not to find aliens, but to figure out how many solar systems and planets are capable of supporting life.”

If a planet were to be habitable, he explained, it would need to be the right size and the right distance from its sun in a “habitable zone” to hold its atmosphere. “It would have to meet lots of conditions.”

Kepler only sees stars; the planets are revealed by the shadows they cast. These shadows cause tiny variations in the brightness of the stars that Kepler can see. The stars also subtly vibrate on their own. "These stellar vibrations can tell us the precise size of the stars – in essence by listening to their pitch. Then the depth of the shadow tells us the size of the planets," said Kawaler.

He finished his talk by sharing with the alumni a bit of good news: NASA just announced it would fund the second phase of the project, what they call K2.

Read more about Kepler:

Kepler spacecraft helps astronomers find tiny planet beyond our solar system

Astronomers with NASA’s Kepler Mission find ‘puzzling pair of planets’

Kepler spacecraft gives Iowa State's Kawaler, astronomers a look inside red giant stars

Kepler Exoplanet Candidates visualization by Jer Thorp

– Steve Jones