This artist's illustration shows stars with multiple planets transiting in front of them. Data form NASA's Kepler Space Telescope has revealed 715 confirmed planets among the 3,601 candidate planets the spacecraft discovered. (NASA)
Using a brand-new technique, scientists using NASA’s Kepler Space Telescope have found 715 confirmed planets huddling around 305 stars, nearly triple Kepler’s previous total of 246 confirmed planets in the Milky Way galaxy. Nearly 95% of them are smaller than Neptune, and four of them are in their star's habitable zone, the region where liquid water – a necessary ingredient for life as we know it – could exist.
The research, which covers the first two years of data after Kepler's 2009 launch, has turned up a smorgasbord of smaller planets – and all in multi-planet systems. The scientists increased the number of confirmed Earth-sized planets by 400%, super-Earths by 600% and Neptune-sized planets by 200%. The number of Jupiter-sized worlds, on the other hand, rose by a mere 2%.
This highlights the transition away from the massive gas giants that characterized Kepler’s first finds and more toward planets that are in the right size range to potentially host life as we know it.
“I’m super excited about this,” said Sara Seager, a planetary scientist at the Massachusetts Institute of Technology who was not involved in the work. The multi-planet systems will help scientists understand our own solar system’s development, she said. For example, many of these systems seem to have multiple planets clustered in an orbit smaller than Venus, or even Mercury. Why are our own solar system’s inner members relatively spaced out?
The findings will also shed light on strange planets like mini-Neptunes, which have no analog in our own solar system, and sharpen scientists’ search for Earth-sized, potentially Earth-like planets, scientists said.
“Nature wants to make small planets,” Seager said.
