Today, December 29, 2009, the New Horizons Pluto probe crosses an arbitrary but psychologically important line: it is now closer to Pluto than it is to Earth. If there were people on board the small interplanetary probe, no doubt they'd be popping champagne. I'm sure that back on Earth, the team behind NH are pretty happy. This probe has a checkered history, having been planned, canceled, re-planned, delayed, on and on. It's amazing it got to launch at all. But on January 19, 2006 the small, half-ton probe was sent on its way, and on July 14, 2015 it'll sail past Pluto and its collection of moons, snapping pictures and taking data. Today marks the official halfway point, where New Horizons has half its path already behind it. Here's a plot of its distance to Earth (in blue) and Pluto (red) care of the New Horizons site:
Distance in the ...
