Comet 67P/Churyumov-Gerasimenko

The comet called 67P/Churyumov-Gerasimenko was discovered in 1969 by the Soviet astronomers Svetlana Gerasimenkova and Klym Churyumov. The comet orbits the Sun in an elliptical orbit that lies between the orbits of Earth and Jupiter. It takes it 6.45 Earth years to make one full orbit around the Sun.



67P/Churyumov-Gerasimenko is one of the best-studied comets. In the years 2014‒2016 the space probe Rosetta had examined the comet, and it even launched the exploratory Philae module to land on comet's surface (the module successfully landed and made important measurements).



The comet has an irregular shape and its diameter is about 4 km. It consists primarily of water ice with an admixture of carbon dioxide, carbon monoxide, methane, ammonia and some simpler organic compounds. Furthermore the comet contains a large amount of a dark stone dust, making it very dark. This material is randomly mixed inside the comet, which is composed from rather irregular ice blocks of a diameter of several tens to hundreds of meters. The large number of small cavities between the blocks are filled with a crushed ice.



For most of its orbit around the Sun, the comet is an inactive frozen body, which we refer to as a comet nucleus. However, once it comes closer to the Sun, its surface begins to heat up and evaporate volatile substances from it. These then surround the comet's nucleus and create its temporary tenuous atmosphere, or halo. The gas and dust particles released from the comet are also formed by the so-called solar wind and they remain scattered along the comet's orbit. In this way, the characteristic comet tail is generated (the tail can be distinguished as plasma tail or dust tail).