Comet trail bright

Comets are celestial bodies made of ice, dust, and rock that develop a bright tail when approaching the Sun. Comet C/2023 P1 (Nishimura) offered a rare spectacle in September 2023.

About this subject

Comets are remnants from the formation of the Solar System, composed mostly of ice, dust, and rocky material. When a comet approaches the Sun, heat causes its ices to sublimate, releasing particles that form a coma (diffuse atmosphere) and one or more tails. The ion tail, blueish, is pushed by the solar wind, while the dust tail, more yellowish, follows the orbital path.

Some comets are periodic, like Halley, which returns every 76 years. Others are discovered suddenly, such as C/2023 P1 (Nishimura), first spotted in August 2023 by amateur astronomer Hideo Nishimura. This comet reached perihelion (closest point to the Sun) on September 17, 2023, becoming visible to the naked eye in the northern hemisphere for a few days. Its tail stretched several degrees across the sky, a fleeting phenomenon that drew observers and astronomers.

Historically, bright comets have been recorded by ancient civilizations as omens. Comet Hale-Bopp (1997) was one of the brightest of the 20th century, visible for 18 months. In contrast, comet ISON (2013) did not survive its close pass to the Sun and disintegrated. A comet's brightness depends on its size, composition, and distance from the Sun. Recent studies, such as those from the Rosetta probe at comet 67P/Churyumov-Gerasimenko, revealed that the surface is darker than charcoal and that gas jet emissions are irregular.

Frequently Asked Questions

Why do comets have tails?

When a comet approaches the Sun, heat causes its ices to sublimate, releasing dust and gases that are blown by the solar wind, forming the tails.

What was the brightest comet ever recorded?

One of the brightest was the Great Comet of 1680, but in modern times Comet Hale-Bopp (1997) was exceptionally bright and long-lasting.

How are comets discovered?

Many are discovered by amateur astronomers or by automated surveys like Pan-STARRS. Comet C/2023 P1 was discovered by Japanese Hideo Nishimura.