Goddard Space Flight Center / NASA

An artist's rendering of Makemake.

The furor surrounding Plutos demotion from planet to dwarf planet back in 2006 still hasnt gone away, but all of the noise much of it coming from disgruntled schoolchildren has obscured the genuinely exciting science underlying that decision. Astronomers began to understand during the 1990s and 2000s that Pluto was just the most visible member of the Kuiper Belt, a vast ring of icy, rocky debris circling the solar system, left from the time the sun and everything that orbits it formed. Little, planet-like bodies called Trans-Neptunian Objects (or TNOs) with names like Quaoar, Sedna, Haumea have joined the Suns family over that time, and when a world named Eris was found to be more or less the same size as Pluto, it became clear scientists would either have to cut the number of planets off at eight, or eventually start counting up into the dozens, at least.

Much more important, though, is the fact that planetary scientists can actually study some of these tiny bodies despite their multi-billion-mile distance from Earth. The latest to come under scrutiny: Makemake (named after the creator god of the Rapa Nui people of Easter Island), which lies about 4.6 billion miles (7.4 billion km) from Earth. Writing in Nature, Jose Ortiz of Spains Andalusian Institute of Astrophysics, along with a long list of colleagues, reports that unlike Pluto, Makemake has no global atmosphere, but that it may have atmospheric patches that hover over parts of its surface. It is, says Ortiz, at least a theoretical possibility.

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Actually, hes being partly humble. Makemake may or may not have patches of atmosphere, but Ortiz and his team know that it doesnt have a complete one because they were able to watch as the world passed directly in front of a background star named NOMAD 1181-0235723. If the atmosphere had been there, the star would have faded out. Instead, it winked out abruptly and winked back in when Makemake emerged from the other side about a minute later.

This sounds pretty simple, but predicting that Makemake would pass in front of this particular unnamed star, in whats known as an occultation, wasnt. From Earth, Makemake appears to be about the size of a quarter sitting 30 miles away (48 km) away, and neither the TNOs orbit nor the stars position was known with great accuracy. When the astronomers found what seemed a good candidate star more or less in the Makemakes path, they calculated whether an occultation was likely, then recalculated over and over as the TNO inched toward the star. In some cases, the encounter never did happen, but on April 23, 2011, the scientists hit pay dirt.

The abrupt off-on of starlight told them part of what they needed to know about Makemakes atmosphere that its not complete. Evidence of its possible patchiness was gathered through remote observations by the space-based Herschel and Spitzer infrared telescopes. They showed that the world has spots of brighter and darker terrain, and because they reflect less light, the dark regions are significantly warmer warm enough, says Ortiz, that methane ice on the surface would be heated to a gaseous state, forming patches of atmosphere.

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In fact, Ortiz says, there might even be some direct evidence for such patches. The occultation was spotted by seven different telescopes, which viewed the passage from just slightly different angles. In some of the telescopes, there was a hint that the starlight didnt wink out quite as abruptly as in the others, suggesting that a patch of atmosphere just happened to be lined up with the star. But, added, Ortiz, we cannot completely rule out an instrumental problem.

Continued here:

Meet Makemake -- the New Pluto