Comet is a celestial body that it has an eccentric elliptical route around the Sun (very long); characteristic for having a cloudy atmosphere around the core and a "tail" made of gases, ice and dust that forms when you get too close to the Sun.
Comets have a very weak glow, reflecting on average only 4% of sunlight, and viewing them with the naked eye is quite rare.
The nebulous and diffuse aspect that surrounds the comet's nucleus, when it passes close to the Sun, is called with the. The comet's tail is formed due to the melting of gases and ice that cover the core of the celestial body. The tail is normally always opposite the Sun and can be millions of kilometers long.
Etymologically, the word comet arose from the Latin commit, which in turn comes from the Greek Komē, which means "hair of the head". The first version of the name was given by the philosopher Aristotle, komētēs, which means "star with hair", when observing the trail left by a comet.
Comets can be classified into three species:
- periodic comets: when the comet has an elliptical orbit around the sun, and it always passes close to the star in periods less than 200 years;
- non-periodic comets: they have parabolic orbits, have been observed only once, and may take thousands of years to reappear again near the Sun, if they do;
- extinct comets: they are comets that no longer exist, either because they collided with another celestial body or because they disintegrated due to a continuous approach of the Sun;
Halley's Comet
Halley is the best-known comet, with an elliptical, periodic orbit around the Sun. Comet Halley passes close to the Sun (perihelion) every 75 or 76 years.
The last appearance of Comet Halley was in 1986, and it is predicted that it will return to be observed with the naked eye on Earth around the year 2061.
Comet Halley was discovered in 1696 by Edmond Halley.
See also the meaning Asteroid.