Geo News

Tail of a comet

After unfulfilled hype that surround­ed the passage of several comets in recent decades, Comet McNaught was a pleasant surprise. It was im­pressively visible from mid-January into early February and can likely still be found with binoculars as it heads away from the Sun towards the outer solar system. Its closest approach to the Sun (perihelion) was on January 12, and like many comets that get fairly near the Sun, it was brighter as it started to move away. This is because the sun's heat causes ice—the main component of comets—to sublimate from the outer skin of the comet and the closer to the sun it gets, the more material is given off. As the ice sublimates, dust is also released. More particles make for a bigger tail, the most strik­ing part of the spectacle. That said, particles in the tail are very sparsely distributed and it is sunlight reflecting off them—like dust motes in a room—that makes the tail visible.


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