Rendezvous Near With “White Collar” Comet

Comets which occasionally visit our skies (thankfully from a distance) after getting dislodged from the depot of the Solar System’s formation debris outside Neptune’s orbit dubbed the “Kuiper Belt” or  the spherical comet reservoir called the “Oort Cloud” much farther away, are generally described as “dirty snowballs”.

But comet  67P/Churyumov-Gerasimenko,  which the Rosetta spacecraft of the European Space Agency (ESA) is approaching for an August rendezvous, may well carry a film of space dust, but idefinitely does not look like snow ball – at least not the ones we make

With a head and a larger body the comet more looks like a snowman in the latest pictures the spacecraft has sent to Earth. 

Astronomers cannot say anything definite yet whether this two-lobbed structure is due to a possible merger of  two smaller comets or to asteroid impacts.

An eye-catching feature of the pictures received on July 20, is the brighter appearance of the narrow “neck” section between the head and the body. According to  ESA experts, this may be a result of a different material covering the area, or a result of an unknown topographical effect.

An alternative explanation for the excess brightness, which makes the “dirty snowman” appear wearing  a spotless white collar, is the later redeposition of the core material to the area corresponding to the comet’s center of gravity after getting kicked up by impacts, thus giving it a smoother texture and enhanced reflectivity.

After reaching its rendezvous, Rosetta will orbit it  and follow the changes its core, – “coma” in astronomy parlance –  will undergo as its goes around the Sun. It will also pull off a space technology first by landing a probe, named Philae, on its surface for more detailed analyses.