Barry Eitel

Our Solar System seems like a pretty tight club. We’ve got the Sun keeping it all together and eight planets, including us, the self-proclaimed “blue marble,” Earth. There’s also a cabal of moons, asteroids and tiny Pluto, which was downgraded (to much Facebook lamenting) to a “dwarf planet” in 2006.

What you might now know, though, is that Pluto actually joined a mysterious group of four faraway dwarfs orbiting our sun, a sect scientists know little about. They do have awesome names, though, like Ceres, Haumea, and Eris (which is actually bigger than Pluto).

The one astronomers are currently excited about is Makemake, a dwarf planet about two-thirds the size of Pluto circling around in the outer solar system. Details about Makemake have eluded researchers until this year, making it the most secretive of the dwarfs.

In April, 2011, Makemake passed between the Earth and distant star Nomad 1181-0235723, allowing astronomers to make crucial judgments about the dwarf’s atmosphere, size and density.

“As Makemake passed in front of the star and blocked it out, the star disappeared and reappeared very abruptly, rather than fading and brightening gradually. This means that the little dwarf planet has no significant atmosphere,” says José Luis Ortiz of Spain’s Andalucian Institute of Astrophysics and leader of the international team that tracked Makemake. “It was thought that Makemake had a good chance of having developed an atmosphere — that it has no sign of one at all shows just how much we have yet to learn about these mysterious bodies.”

Makemake’s distance means observing the dwarf is difficult and stellar occultations (when an object passes between the Earth and a star) are very rare because it orbits in a region with few stars. Observers cobbled together data from several telescopes around South America, especially a handful in Chile.

The international effort required intense collaboration and attention to detail. Timing was critical; Makemake only blocked the light of Nomad 1181-0235723 for about a minute.

Astronomers originally thought chilly Makemake had developed an atmosphere like Pluto or Eris, but this appears to not be the case.

“Pluto, Eris and Makemake are among the larger examples of the numerous icy bodies orbiting far away from our Sun,” Ortiz continues, “Our new observations have greatly improved our knowledge of one of the biggest, Makemake — we will be able to use this information as we explore the intriguing objects in this region of space further.”