What color is Pluto? The answer, revealed in the first maps made from New Horizons data, turns out to be shades of reddish brown. Although this is reminiscent of Mars, the cause is almost certainly very different. On Mars the coloring agent is iron oxide, commonly known as rust. On the dwarf planet Pluto, the reddish color is likely caused by hydrocarbon molecules that are formed when cosmic rays and solar ultraviolet light interact with methane in Pluto’s atmosphere and on its surface.
New Horizons is a NASA probe launched years ago when Pluto was still the ninth planet. It will make it’s closet approach on Tuesday July 14th, but we’re already learning new things and confirming previous suspicions. Somehow I had missed that Pluto is red like Mars, but for different reasons.
I had thought to take July 14th off, but after reviewing the list of announced media activities, decided not to. No flyby images will be released that day. It looks like New Horizons will send a “I made it!” signal expected to be received around 4:15pm Alaska Time on July 14th, so I will look for that. As of this writing, flyby images are expected to be released sometime in the afternoon of the July 15th. Tune into NASA television when that happens. I’ll let you know if I hear about a more precise time for the image release.
In terms of space exploration, I think it’s a good time to be alive.