How do comets work

But while asteroids are generally comprised of rock and metal, comets are more akin to dirty snowballs. They are composed of frozen gases such as carbon dioxide, methane, and ammonia, as well as water ice, in which dust particles and rocky material are embedded. As a comet approaches the Sun, solar radiation "melts" the surface, vaporizing molecules of gas and dust and creating the brilliant tail comets are best known for.

A comet's tail will always point away from the Sun, which means it doesn't always trail behind the comet on its journey, but rather can travel beside or in front of it. Comets spend most of their lives far away from the Sun in the distant reaches of the solar system. They primarily originate from two regions: the Kuiper Belt, and the Oort Cloud.

The Oort Cloud is at the edges of the Sun's gravitational influence about 50, to , AU and divided into two regions: the inner, disc-like Hills cloud, and the outer spherical cloud, both composed of icy bodies. Though billions more are thought to be orbiting the sun beyond Neptune in the Kuiper Belt and the distant Oort cloud far beyond Pluto. Occasionally, a comet streaks through the inner solar system; some do so regularly, some only once every few centuries.

Many people have never seen a comet, but those who have won't easily forget the celestial show. A comet primarily consists of a nucleus, coma, hydrogen envelope, dust and plasma tails. Scientists analyze these components to learn about the size and location of these icy bodies, according to ESA. The nucleus is the solid core of a comet consisting of frozen molecules including water, carbon monoxide, carbon dioxide, methane and ammonia as well as other inorganic and organic molecules — dust.

According to ESA the nucleus of a comet is usually around 10 kilometers across or less. As a comet gets closer to the sun, the ice on the surface of the nucleus begins turning into gas, forming a cloud around the comet known as the coma. According to science website howstuffworks.

Surrounding the coma is a hydrogen envelope that can be up to 6. As the comet gets closer to the sun, the hydrogen envelope gets bigger. There are two main types of comet tails, dust and gas. Comet tails are shaped by sunlight and the solar wind and always point away from the sun according to Swinburne University of Technology. According to NASA, comet tails get longer as a comet approaches the sun and can end up millions of miles long.

The dust tail is formed when solar wind pushes small particles in the coma into an elongated curved path. Whereas the ion tail is formed from electrically charged molecules of gas. Comet tails may spray planets, as was the case in with Comet Siding Spring's close encounter with Mars. The dust present in the coma does not get affected by the magnetic fields but vaporises by the heat of the Sun.

As a result, a curved tail is formed which follows the orbit of Comet. It has been seen that comets are named after their discoverer. For example, Comet Halley is named for Edmund Halley. He determined that Comets observed in , , and had the same orbits and were a single comet. According to Edmund Halley's calculations, he in predicted correctly about the comet's return but unfortunately, he did not live to see Halley Comet. Sometimes it is seen that more than one person reports a new comet at the same time.

The nucleus of a comet is usually 1 to 10 kilometres that is 0. The tail can stretch for tens of millions of kilometres. It is believed that comets have two sources namely Long-period comets and short-period comets. Long-period comets take more than years to complete an orbit around the Sun whereas short-period comets take less than years to complete an orbit around the Sun. They originate from the Kuiper Belt.

According to Danish astronomer, Jan Oort comets reside in a huge cloud at the outer reaches of the solar system, far behind the orbit of Pluto. This is known as the Oort cloud. According to some statistics, it may contain trillion comets and may account for a significant fraction of the mass of the solar system. JPL's lucky peanuts are an unofficial tradition at big mission events. It's suspected that about 5, years ago a comet swept within 23 million miles of the Sun, closer than the innermost planet Mercury.

Models and lab tests suggest the asteroid could be venting sodium vapor as it orbits close to the Sun, explaining its increase in brightness. A one-time visitor to our inner solar system is helping explain more about our own origins. A wayward young comet-like object orbiting among the giant planets has found a temporary parking place along the way. As Chile and Argentina witnessed the total solar eclipse on Dec. When scientists downlinked data from Parker Solar Probe's sixth orbit, there was a surprise waiting for them: a sungrazing comet.

Two Views of a Sungrazing Comet.