The Kuiper

It is with a touch of irony that the belt of far away objects circling the inner planets is know as the “Kuiper Belt” considering that the man it is named after, Gerard Kuiper, pointed out in his theory that such a belt as this could have existed, but was surely long gone. The name, still a hotly contested one in the field of astronomy, has stuck, however. What is found inside the belt is even more interesting than the story of how it was named.

A Look at the Kuiper Belt

The Kuiper (pronounced like “viper”) Belt is similar to the asteroid belt in our solar system, but much larger, much denser, further away, and with different content. Where the asteroid belt is known to be comprised of a field of objects mainly of metal and rock, the Kuiper Belt Objects (KBOs) are mostly made of ice, including methane and ammonia in addition to water. The Kuiper Belt was postulated in one form or another as far back as 1930, shortly after the discovery of Pluto, to 1951 by Kuiper himself, and 1964 when Fred Whipple hit on the “dirty snowball” truth about comets. It was in 1977, however, when the first evidence of such a belt was discovered.

Charles Kowal discovered an icy planetoid called 2060 Chiron between Saturn and Uranus. A follow up discovery of a second object in the same region would have to wait until 1992, followed soon after by a third. At this point the discoveries of these last objects, David Jewitt and Jane Luu, referenced the words “Kupier” and “comet belt” so often in the beginning of their paper on the matter that it became known as the “Kuiper Belt.”

The Make up of the Kuiper Belt

It is believed that the Kuiper Belt starts at about 30 AU from the Sun and stretches out to about 55 AU, after which it abruptly ends. It is believed there may be a planet there that effectively “cleared the surrounding space” due to its gravitational effects. Interestingly it is because of the discoveries of the Kuiper Belt that this hypothesis has come about. Because so many objects similar to Pluto in composition, size and the presence of satellites were discovered in the Kuiper Belt, the International Astronomical Union was forced to define what a planet was for the first time. It was decided that a planet has to clear the surrounding space, which has lead to Pluto being reclassified as a KBO.

There are objects roughly the size of Pluto and larger in the Kuiper Belt, some approaching 1500 kilometres. It is believed that Jupiter’s moon Triton is a captured KBO, rather than a satellite that formed around the planet as Earth’s moon did. The hypothetical Oort Cloud is thought to be the origin of long term comets like Halley’s, but short term comets had to come from a closer source—it is thought the Kuiper Belt is that source, and it was this speculation that lead to the thought path that eventual resulted in the discovery of the belt.

Final Thoughts

In the discovery of the Kuiper Belt the very textbooks used to teach children science have been changed. Pluto is no longer a planet, the Oort Cloud is not the only source of comets, and there are thought to be over 700,000 objects to be discovered yet in the Kuiper Belt.

Related Articles in the 'Our Solar System' Category...

• A Guide To The Outer Solar System
• How Planetary Surfaces Are Formed
• Observing Dark Matter And The Lifespan Of The Universe
• Orbits and How They Work
• Origins of the Solar System
• Planetary Atmospheres
• The Asteroid Belt
• The Discovery of our Dented Solar System
• The Dwarf Planets
• The Gas Giant Planets
• The Rocky Planets