Comets From Beyond Our Solar System

Amateur astronomers enjoy looking up into the heavens to not only observe the planets and stars but also the approach of comets, many of which provide a dazzling display. Many of these marvelous objects can be seen with binoculars or even the naked eye.

The appearance of a comet within view of Earth is definitely an occasion of world wide significance. You only have to witness the massive media attention that the Haley or Hale-Bopp had when they came within view. The mere sight of these remarkable space objects is both frightening and awe inspiring at the same time.

During these times it tends to bring out the budding astronomer in all of us. But what exactly is a comet and where did it come from? And how does it produce that spectacular tail?

A comet is a small icy solar system body, which when close enough to the Sun, displays a visible coma (a fuzzy, temporary atmosphere) and quite often a tail.

This phenomena is due to the effect of solar radiation and solar wind upon the nucleus of the comet. Comet nuclei range between just a few hundred meters to tens of kilometers across and are composed of loose collections of ice, dust, and small rocky particles.

However we should not confuse comets with asteroids,which are small space rocks that come from an asteroid belt between Mars and Jupiter. While still quite stunning to see, they pale in comparison to the arrival of a comet.

One scientist called the make up of a comet as much like a “dirty snowball” simply because the composition is so diverse and changeable. The center or nucleus of a comet is normally quiet solid but the “snowball” materials often create a “cloud” around that nucleus that can become rather large and can extend to great lengths behind the comet as it moves through space. That trailing plume is what makes up the comet’s magnificent tail and what makes it so fascinating to observe.

There are many theories about where they come from, but it is clear that they originate from outside our solar system, somewhere in deep space. Many have speculated they are fragments remaining from the organization of planets that get loose from gravitational pull and are sent flying through space to end up in the gravitation pull of our Sun bringing them into our solar system.

Yet another theory is that they come from a gaseous cloud called the Oort cloud, which is cooling after the organization of the sun. As this space debris cools, it gets organized into one body which then gathers sufficient mass to be attracted into the gravity of our solar system turning into a fast moving comet plummeting toward our sun.

However, a result of the strong gravitational orbits of the numerous planets in our solar system, a comet does not always immediately collide with the sun but very often takes on an orbit of its own.

The life span of comets varies enormously. Scientists refer to a comet that is predicted to burn out or impact the sun within a two hundred year period as a short period comet, as opposed to a long period comet which has a life span of more than two hundred years. Now that might seem a long time to us but in relation to planets and stars, this is an incredibly short lifespan.

While many science fiction authors and tabloid newspapers like to alarm us with the potential for a comet impacting the earth, scientists who are aware of the orbits of comets and what causes their path to change inform us that this is extremely unlikely.

This year, 2011 there has been plenty of speculation on a new arrival in our solar system. Called Comet Elenin it is due during september and could provide an interesting show.

That's good news for us because some comets are as big as a planet, so that impact could be devastating. For the time being, we can enjoy the excitement of witnessing comets make their rare visits to our night sky, and marvel at the spectacular shows that these visitors from outer space put on when they're visible in the cosmos.

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