ESO/L. Calçada/Nick Risinger (

ScienceShot: Breathless Orb

Data gathered when the dwarf planet Makemake passed in front of a distant star last year are shedding new light on the icy orb's size, shape, and atmosphere—or, more precisely, its lack of one. Named for a god of the Rapa Nui culture of Easter Island, Makemake (artist's concept, above) orbits in the frigid realm far beyond Pluto and was about 7.7 billion kilometers from Earth when the brief eclipse occurred. As the dwarf planet's shadow passed across eight telescopes at five sites in central South America, it blocked light for intervals ranging from 59 seconds to 66 seconds, suggesting that Makemake is a 1500-by-1430-km ellipsoid, researchers report online today in Nature. Because the amount of light reaching the telescopes dropped abruptly at the beginning of the eclipse, rather than gradually, and rose sharply at the end of the event, the team suggests that Makemake has no global atmosphere—or, at best, a wisp of methane atmosphere with a surface pressure no more than 12-billionths that of Earth.

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