Unlike its bigger sister Pluto, dwarf planet Makemake doesn't have an atmosphere, new observations have revealed.
About two thirds of the size of Pluto, Makemake orbits further out, although it's closer to the sun than Eris, the most massive known dwarf planet in the solar system.
Previous observations have shown it to be similar to its fellow dwarf planets, leading some astronomers to expect its atmosphere, if present, to be similar to that of Pluto.
The team used the Very Large Telescope (VLT), New Technology Telescope (NTT), and Trappist (TRAnsiting Planets and PlanetesImals Small Telescope) telescopes with data from other small telescopes in South America to look at Makemake as it passed in front of a distant star.
"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 Jose Luis Ortiz of the Instituto de Astrofisica de Andalucia in Spain.
"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. Finding out about Makemake's properties for the first time is a big step forward in our study of the select club of icy dwarf planets."
Not much was known about Makemake, and the team's new observations give much more detail about its size, atmosphere and density. They've also established its albedo, 0.77 - comparable to that of dirty snow and higher than Pluto's, but lower than that of Eris.
"Pluto, Eris and Makemake are among the larger examples of the numerous icy bodies orbiting far away from our Sun," says Ortiz.
"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."