2:45 PM | We've never seen Pluto close up...until now

[Image of Pluto taken by NASA's New Horizons spacecraft on July 7th; courtesy NASA]

Discussion

It took NASA’s New Horizons spacecraft nine years to cover the 3 billion mile trip there, but come next Tuesday, July 14th, it’ll fly within 7,750 miles of Pluto and show us the dwarf planet and its five moons for the first time. Pluto is the farthest destination for any space mission in history and because New Horizons is traveling at such a high speed (~31,000 miles per hour) and can’t slow down, the flyby will be over in a matter of minutes. This brief encounter with Pluto will mark the first time since 1989 – when Voyager 2 probe fled by Neptune – that we’ll be seeing an entirely new world for the first time. Not even the Hubble Space Telescope could see the dwarf planet clearly, but those days are over.

In fact, over the past few weeks New Horizons has closed in on Pluto giving us better and better photos including the one above taken on July 7th from about 5 million miles away. While this photo is a big improvement from anything captured beforehand, it is nothing compared to what will come later next week after closest approach. The images taken at closest approach next Tuesday will actually not be available for viewing until a couple of days later (7/16), and they are expected to reveal high-resolution geological features on the surface of Pluto. They could reveal mountains, ice caps, volcanoes, or even an ocean of liquid water under ice – nobody knows for sure.

Pluto is quite unusual in that it is a fraction of the size of the Earth and yet has five moons. The dwarf planet slightly orbits the largest moon, Charon, leading some to suggest that the pair could be best described as a double planet system. Charon is about 750 miles across and half the diameter of Pluto – making it the solar system’s largest moon relative to its planet. Three of the smaller moons are swept up in the pair’s gravitational field which leads to bizarre and chaotic orbits of their own.