A NASA spacecraft speeding toward Pluto is casting a wary eye on the dwarf planet system, looking for anything that could trip it up in the home stretch of its historic mission. NASA's New Horizons ...

Do you miss Pluto? In 2006, the International Astronomical Union voted this bantam world off the island. It was no longer a planet — a peer of Mars, Jupiter and the rest. From then on, Pluto was to be ...

This week, the small and distant dwarf planet Pluto will reach opposition, the time of the year when the object is closest to Earth and brightest in the sky. As a happy coincidence, the moon will be ...