Alan Stern, principal investigator for the New Horizon mission, reveals his biggest surprise so far as the probe closes in on Pluto. (Recorded 12 July 2015.)
A four-planet system orbiting the star Kepler-223 in the constellation Cygnus is actually a rarity: Its planets, all miniature Neptunes nestled close to the star, are orbiting in a unique resonance that has been locked in for billions of years. For every three orbits of the outermost planet, the second orbits four times, the third six times and the innermost eight times.
NASA’s New Horizons spacecraft, speeding toward deeper space at more than 32,000 miles per hour, has successfully performed a series of targeting manoeuvres that set it on course for a January 2019 encounter with Kuiper Belt object 2014 MU69. This ancient body is more than a billion miles beyond Pluto. The propulsive manoeuvres were the most distant trajectory corrections ever performed by any spacecraft.