Comet
A comet is a small Solar System body composed mainly of ice, dust, and organic compounds. As they approach the Sun, cometary ices sublimate, releasing gas and dust that form the glowing coma and distinctive tails—often extending millions of kilometers.
Comets originate from two primary reservoirs: the Kuiper Belt—home to short-period comets with orbits under ~200 years—and the distant Oort Cloud, which sends long-period comets with orbits spanning thousands of years. Occasionally, interstellar objects like ‘Oumuamua pass through our system, appearing comet-like.
They are “dirty snowballs” and among the most primitive remnants of the early Solar System, preserving original ices and organic material from 4.6 billion years ago.
Landmark missions include ESA’s Rosetta—with its lander Philae—which orbited and sampled Comet 67P/Churyumov–Gerasimenko (2014–2016). NASA’s Deep Impact struck Comet Tempel 1 in 2005 to analyze interior composition.
These missions discovered complex organic molecules, including amino-acid precursors, and supported the theory that comets may have delivered water and prebiotic compounds to early Earth.
Looking ahead, ESA–JAXA’s Comet Interceptor (launch planned for 2029) intends to perform a rapid flyby of a dynamically new or interstellar comet, using multiple spacecraft to sample both nucleus and coma environments.
Comets are studied across the electromagnetic spectrum—from radio to gamma rays—using telescopes and spacecraft to understand composition, internal structure, activity, and their roles in planetary formation, the evolution of the solar system, and the origin of life.
Sources
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Waterfalls, Auroras, Comet: Iceland
26 March 2013
If not distracted by the picturesque landscape, waterfalls, stars, and auroras, you might be able to find Comet PANSTARRS. The above image, capturing multiple terrestrial and celestial wonders in a single shot, was taken last week in southwest Iceland. The popular Gullfoss waterfalls are pictured under brilliant auroras that followed a M1-class solar flare and powerful Coronal Mass Ejection two days earlier. Give up on locating the comet? Comet PANSTARRS is faintly visible as a light blip just above the horizon toward the left of the above image. The comet remains more directly visible to northern observers with binoculars looking toward the western sky just after sunset. Gallery: Comet PANNSTARS