wonderful universe
Comets
The IAU ’ s definiton of comet is : A comet is a body made of rock and ice , typically a few kilometres in diameter , which orbits the Sun . Comets may pass by the Sun only once or go through the Solar System periodically . A comet ’ s tail is formed when the Sun ’ s heat warms the coma or nucleus , which releases vapours into space . After the Discovery it is given a designation to the comet according the following IAU ’ s Resolution C5 adopted by IAU in 1995 : “ A prefix , alluding to the type of comet , which can be any of the following :
• P / for a periodic comet .
• C / for a comet that is not periodic .
• X / for a comet for which a meaningful orbit cannot be computed .
• D / for a periodic comet that no longer exists or is deemed to have disappeared .
• I / for a comet originating from interstellar space .
• The year of discovery . An uppercase letter identifying the half-month of observation during that year ( A for first half of January , B for second half and so on ). A number representing the order of discovery within that half month .” ( Reference : https :// www . iau . org / public / themes / naming /# comets ) For example , the second periodic comet discovered on the first half of April 2020 will receive the designation comet P / 2020 G2 “ To complete the designation , a comet is given the name of its two
first discoverers ” An example is the comet D / 1993 F2 know as Shoemaker- Levy 9 . A total of 13 spaceships developed by United States , Soviet Union , Japan and the European Space Agency already visited comets . Rosetta was the last mission to reach a comet . The mission was composed by a saceship and a lander module , called Philae . On Augst 6th , 2014 , the spacecraft reached the comet 67P / Churyumov – Gerasimenko . The probe Philae on November 12th , 2014 , was the first lander
developed to the humanity to land in a comet !!! The Rosetta mission sent fantastic data and wonderful images of the comet and its surface !!!
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