Astronomers get rare glimpse of dwarf planet
FRANCE: A rare dalliance with a star in a remote part of our Solar
System has allowed scientists to glean data on a distant, icy dwarf
planet about which we knew very little before, astronomers said
Wednesday.
They had expected to find an atmosphere similar to that of Pluto on
the planet named Makemake but instead saw “no sign of one at all”, the
group wrote in the journal Nature.
They also discovered that Makemake, one of five dwarf planets known
to exist on the edge of our Solar System, reflected more light from the
Sun than its near neighbour Pluto.
Makemake reflected 77 percent of the Sun's light compared to Pluto's
52 percent -- akin to the reflective power of dirty snow, the team
reported.
Makemake is about two-thirds the size of Pluto and orbits at a
distance of about 7.8 billion kilometres from the sun -- somewhere
between Pluto and Eris, the biggest and most distant of the known dwarf
planets.
Previous observations had shown Makemake to be similar to its fellow
dwarfs in many ways, leading some to expect that its atmosphere would
resemble Pluto's, said a statement issued by the team led by Jose Luis
Ortiz of the Instituto de Astrofisica de Andalucia in Spain.
To make its observations, the team had to wait until Makemake passed
in front of a distant star, which happened on April 23, 2011, and then
trained seven telescopes in Brazil and Chile on the mysterious body. “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,” said Ortiz. “This means that the little dwarf
planet has no significant atmosphere.” Makemake's lack of moons and its
great distance from us make it difficult to study. But with their new
observations, the team was able to glean new data about the planet's
size and density.
The concluded it is a sphere slightly flattened at the poles -- its
polar equatorial axis about 1,430 kilometres. “Makemake was the
poorest-known dwarf planet and thanks to our study we have revealed
several important properties of this body,” Ortiz told AFP.
AFP |