6) It has an atmosphere
OK, if you're a regular reader of this blog
you already knew that. But it still surprises me, so maybe it surprises you too. After all, Pluto is a long, long way from the Sun, and it's so cold that's it's hard to imagine anything being able to stay a gas there.
But there is air there, though a little thin for our taste (the atmsopheric pressure at the surface is about 0.00001 times that of the Earth). Pluto's atmosphere is mostly nitrogen, with a whiff of methane tossed in. Methane is a greenhouse gas, so that does help warm the little iceball up a bit. Also, recent observations indicate that when Pluto is nearer the Sun, as it is now, the frozen stuff on its surface turns directly into a gas (the process is called
sublimation). This takes energy away from the surface and gives it to the gas, in much the same way that evaporating sweat takes heat away from your skin. That process cools your skin, and on Pluto it cools the surface, so, oddly, Pluto's air is much warmer than the surface. Though, at 170 below 0 Celsius, it ain't exactly Hawaii.
Still, the fact that atmosphere of Pluto is mostly nitrogen is oddly comforting to me. After all, so is the air you're breathing now!