The European Space Agency probe has been studying the comet and beaming data back to Earth.
Rosetta has observed that the comet is made up of fluffy layers of dust and ice, with a density half that of water. Scientists have also observed that there are unusual cylindrical pits on its surface, whose walls are covered in what appear to be goosebumps. The report and accompanying photos were published in the journal Science.
Two comets for the price of one?
Perhaps most interestingly of all, it can be seen that the comet is formed of two sections joined by a neck, reminiscent of a rubber duck. A deep crack has been observed in this neck section. At points the crack is around a meter wide, and some areas are filled with dust.
Scientists postulate that stresses caused by the flexing of the comet caused the crack. They claim that its possible that it could close up, or that it could grow even larger and the comet could eventually split in two.
Rosetta has taken a series of measurements which would give the comet a mass of 10 billion tonnes. However the low strength of its gravitational field means that the body of the comet is fluffy, with porosity measured between 70 and 80%.
The comet is losing vast amounts of material as it approaches the sun, with the majority coming from the cracked neck area, where gravity is weakest. This means that when dust becomes dislodged from the surface it is able to drift into space instead of being pulled back to the surface of the comet.
The comet will pass closest to the sun in August of this year, and Rosetta will fly through the jets of dust and gas released from its surface during its most active period, in order to analyze their chemical composition and hopefully improve our knowledge of comet formation.
Rosetta has already made some interesting observations, one of which throws into doubt a popular theory. Analysis has shown that water on the comet is not the same as that found on Earth, which goes some way to disproving the theory that comets were responsible for bringing water to Earth, thereby making it habitable.
“This is a wonderful time for exploring the building blocks of our solar system,” said Holger Sierks, lead scientist on Rosetta’s Osiris camera. “It is the first time ever that we can see how a comet really works.”