How many planets are there? Not long ago the answer to that question was simple: eight, or nine if you counted Pluto (now officially a dwarf planet). The only planets known to exist were the ones in our own solar system.
NASA's Kepler probe has changed all that. So far the space-based telescope has confirmed the existence of 978 extrasolar planets (exoplanets) and found more than 4,000 so-called "planet candidates." Those numbers could rise as NASA continues to crunch the data.
But Kepler might never have gotten off the ground without the perseverance of William Borucki, the mission's principal investigator and a NASA legend whose career at the agency has spanned more than half a century.
As Borucki explains in this recent interview with HuffPost Science editor David Freeman (click on the link above to listen), it took years of R&D--and lots of wrangling--to get the agency to proceed.
The interview was originally broadcast on Sharon, Connecticut radio station WHDD/Robin Hood Radio. Scroll down more Science Insider interviews.