Comets are celestial bodies in space that orbit the Sun. These icy bodies often release gas and dust in their wake. Also, they are often compared to dirty snowballs. Comets contain dust, ice, carbon dioxide, ammonia, methane, and other compounds. Likewise, astronomers believe that they were formed in the solar system about 4.6 billion years ago.
Some researchers believe that comets may have brought back to Earth some of the water and organic molecules that now make up life here. However, this hypothesis is still being investigated, so astronomers are analyzing the nucleus and environment of comets.
Comets characteristics
According to NASA, the nucleus of a comet is made up mainly of ice and dust coated with dark organic material. Ice is mostly made up of frozen water, although it could also contain other substances such as ammonia, carbon dioxide, carbon monoxide, and methane.
As a comet approaches the Sun, the ice on the surface of the nucleus transforms into gas, forming a cloud known as a coma or scalp. Radiation from the Sun pushes dust particles away from the cloud, forming a dust tail. Meanwhile, the Sun’s particles convert some of the gases into ions, forming a tail of ions. In addition, since the tails of comets are formed by light and solar wind, they always point in the opposite direction to the Sun.
Comets’ nuclei are 10 miles or less. However, some comets have commas that can reach 1.6 million kilometers across. In addition, some have tails that are more than 100 million miles long.
Comets can be seen with the naked eye as they pass close to the Sun because their commas and tails reflect sunlight or even glow from the energy they absorb from the Sun. However, most comets are too faint or small to observe without a telescope.
