If you combine many of the materials found in the solar system — rocks, water, methane, nitrogen, carbon-mo**xide — and assemble them into an object far from the sun, pummel it with impacts from other objects in the solar system and then wait billions of years, you might produce something like Pluto.
Scientists have some sense of this recipe because*they got their first close-up look at the underdog dwarf planet when NASA's New Horizons spacecraft flew past Pluto in July, beaming back breathtaking images of the complex geology and atmosphere of a world never studied from close range. Read more...