Click here to see the animation of the motion of a comet.
Comets are characterized by their particular morphology :
-the core, center of the bright area, the size of which rarely exceeds 3 km and is made of ice, snow and mixed rocks ;
-the tail or coma very bright around the core made of water vapor and carbon dioxide enhanced by solar radiation ;
-a neutral hydrogen envelope a million kilometers around the comet ;
-the dust tail made of rock debris ejected with sublimated gas; it can reach 10 million kilometers long ;
-the ion tail made of plasmas interacting with the solar wind and may reach 100 millions kilometers long ;
- a highly eccentric orbit that regularly brings the comet in the vicinity of the Sun.
Opposite, the comet Hale-Bopp where we distinguish very well the blue ion tail and white dust tail. Many observations of this comet were made.