NASA'S DAWN SPACECRAFT has begun approaching Ceres ahead of a historic March arrival at the mysterious dwarf planet.

Dawn has officially entered the Ceres approach phase, after recently emerging from behind the sun relative to Earth and thus coming back into reliable communication range. The probe is now about 400,000 miles from Ceres and is cruising toward the 590-mile-wide object at 450 mph , NASA officials said.

Dawn should enter orbit around Ceres — the largest object in the main asteroid belt between Mars and Jupiter — on March 6, 2015. When that happens, the spacecraft will become the first ever to orbit two different unexplored solar system bodies. (Dawn circled the protoplanet Vesta, the asteroid belt's second-largest object, from July 2011 through September 2012.)

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