Warwick in new planet discovery

Astrophysicists at the University of Warwick are part of a research team which has made new discoveries about a dwarf planet called Makemake.

Makemake is a dwarf planet in the outer Solar System farther out from the Sun than Pluto; it is estimated to be five thousand miles away from Earth.

In April 2011, as Makemake passed in front of a star and blocked its light (known as Stellar Occultation), scientists were able to investigate the planet’s properties.

Some of the observations were made using a high speed camera called ULTRACAM, run by the University of Warwick and the University of Sheffield. The camera showed that the passing planet blocked the stellar light for fifty-nine seconds.

It was expected that Makemake’s atmosphere would be similar to Pluto’s, as previous observations suggested that Makemake and Pluto were fairly similar. However, recent observations suggest that Makemake does not have an atmosphere.

Jose Luis Ortiz, head of the research team and member of the Instituto de Astrofísica de Andalucía in Spain, explained: “As Makemake passed in front of the star…the star disappeared and reappeared very abruptly, rather than fading and brightening gradually. This means that the little dwarf planet has no significant atmosphere.”

Nonetheless, scientists do not exclude the possibility that Makemake could have an atmosphere that covers only part of its surface.

The albedo, a measure of light reflected from the planet’s surface, is measured to be about 0.77, higher than that of Pluto. The high albedo, along with its lack of atmosphere and its distance from the Sun, suggests that Makemake is colder than Pluto.

It is estimated that Makemake is shaped as an oblate spheroid with an approximate diameter of 1450 kilometres, which is approximately two-thirds the size of Pluto. It is also estimated that the planet’s density is about 1.7 grams per cubic centrimetre.

Because of Makemake’s distance from the Earth, its lack of moons and its direction from the Earth where there are relatively few stars, it is difficult to make observations about the planet.

Ortiz believes that recent observations show “just how much we have yet to learn about these mysterious bodies”.

He added: “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.”