sungrazer comet

A sungrazer comet is a comet with an orbit that brings it extremely close to the Sun, and many such comets are destroyed in an instant due to intense heat and other effects when they approach too closely. Because they pass so near the Sun and are subjected to extreme temperatures and related influences, they are a special class of comets known for rapidly disintegrating immediately after perihelion.

about 76 years

Halley’s Comet is a periodic comet that passes near Earth about every 76 years. It travels in an elliptical orbit around the Sun, and it can be seen with the naked eye from Earth at roughly the same 76-year interval. It was last observed in 1986 and is expected to be observed again in 2061.

when the comet was closest to the Sun

When a comet approaches the Sun, its temperature rises and the ice and gases on its surface vaporize, forming a tail. It appears brightest in this state and is best for observation. This is called perihelion passage. As it gets closer to the Sun, heat releases gas and dust, creating a tail and making it brighter, so it becomes easier to see from Earth.

Effects of sunlight and the solar wind

When a comet approaches the Sun, its ice and dust evaporate due to the Sun’s heat. The solar wind and the pressure of sunlight then push the gas and dust that have escaped from the comet’s nucleus away to the side opposite the Sun, forming a “tail.” As it comes closer to the Sun, the heat causes gas and dust to be released.

the opposite direction of the sun

A comet’s tail always extends in the direction opposite the Sun due to the solar wind and radiation pressure. It doesn’t necessarily point along the comet’s direction of travel or behind it. As the comet approaches the Sun, the tail appears and is pushed by the solar wind, so it stretches away from the Sun.

Oort Cloud

Many comets are thought to come from a spherical region even farther out than the solar system, called the Oort Cloud. The Oort Cloud is a place where numerous ices and rocks are gathered. It is believed that long-period comets come from the Oort Cloud, far beyond the outer reaches of the solar system.

ice

A comet’s nucleus contains the most ice, and also includes substances such as carbon dioxide and ammonia. When the Sun’s heat causes the ice to sublimate, it releases gas and dust, forming the comet’s tail. Because comets spend long periods in the cold, dark reaches of space, they contain a lot of ice.