Jason Steffen is associate professor of physics at the University of Nevada, Las Vegas. A longtime science team member of NASA's Kepler mission, he has contributed to the discovery and characterization of thousands of exoplanets that orbit distant stars. In the first half, he shared insights into the journey of the Kepler mission and its groundbreaking discoveries. Launched in 2009, Kepler operated for about four years and then was repurposed in what was known as the K2 mission, providing an additional five years of data. He explained the distinctions between Kepler and the Hubble Space Telescope-- Kepler was designed to be very precise at making measurements of stars, which allowed it to identify over 2,700 new planets, while Hubble was more adept at taking stunning photos.
He noted that when Kepler launched, no planets were known outside of the solar system, and its mission was to find Earth-like worlds. The data revealed an unexpected diversity of planets. "The typical planet that Kepler found is about three to five times the mass of the Earth," he reported. Among Kepler's remarkable findings were "hot Earths," planets similar in size to Earth but orbiting their stars in just one day, leading to extreme conditions. "If you were on the surface of one of those planets, the sun...would fill half the sky...[and] you'd be swimming in a sea of molten rock," he marveled.
The conversation shifted to the possibility of intelligent life beyond Earth. Steffen shared insights from his colleague David Kipping, who posits that "if life formed really quickly on the Earth... then it's easy for life to get started." Recent fossil discoveries suggest life on Earth began much sooner than previously thought, making the existence of life elsewhere in the galaxy seem more plausible.