Astronomical Comets: Voyagers From Outer Space

Comets which can be clearly seen by the human eye are a rarity. Out of millions of comets that orbit the sun, usually just one a year can be visible without the aid of a telescope. However, there are almost 3,500 named and known comets. But of course there are millions yet to be named and still unknown.

Comets are giant snowballs of ice and dust that orbit the sun. Some comets take thousands of years to orbit the sun as their rotation is vast. Other comets complete their rotation every 3 years.

Comets are different from meteors in that they orbit the sun. Meteors are pulled into the earth's atmosphere from other places.

In ancient times, before the advancements of science a comet was viewed as a warning to a catastrophe. If a comet was seen astrologers would forecast doom and impending tragedy.

Great Comet

Still pictures of a comet.

 17/P Holmes through a telescope

Some scientists believe that comets are particles that are millions of years old, which helped form the planets that linger on the outside of our galaxy. These planets are Uranus and Neptune. These ancient particles may well hold the key and answers to how our own solar system was formed.

Nucleus of comet-Snowballs of ice and dust:

Halley's Comet

Hale-Bopp Comet 1997:

One famous comet watcher was Edmond Halley. He successfully predicted the return of a particular comet every 76 years and this comet was named “Halley's Comet” in his honor. “Halley's Comet” is scheduled to make its rotation past earth again in 2061. This comet's average speed is 150,000 miles per hour.

Halley's Comet in 1986:

Back in 1994, Jupiter's atmosphere literally sucked in a comet and it created a spectacular collision. It looked like the atmosphere of Jupiter was going through a series of explosions or being literally “bombed.”

Comet Image:

Most comets are not visible to the human eye. Deep in the solar system a comet has a nucleus made of ice, gases, rock and metal. As a comet nears the sun it causes the comet to become illuminated and more visible.

An average comet is about 60,000 miles wide. The closer a comet is to the sun, the brighter the comet and the larger the comet due to the sun's radiation on the particles.

Footage from Hubblecast/NASA

Not only will a comet become more visible as it approaches the sun, but it also changes and can have a tail that is 90 million miles in length!

.A comet can travel at various speeds and will increase in speed the closer it is to the sun.

Short period comets take less than 200 years to travel around the sun. One known comet's rotation is a short 3.3 years. Most comets have a rotation far beyond Neptune. This area is called the “Kuiper belt.” Halley's Comet is from this region. Comets which have rotations in thousands of years are from the part of the solar system called “Oort cloud.”

A collision of a comet on earth could be catastrophic, yet it is unlikely. Astronomers are always watching the skies for any comet which may pose potential harm to earth.

The particles, dust and ice which compose comets may well be millions of years old and date back to the beginning of our solar system. By studying this amazing phenomenon we may gain an understanding of our own origin and our place in the great universe.