Kuiper Belt

The Kuiper Belt, sometimes called the Edgeworth–Kuiper belt, is a region of the Solar System beyond the planets extending from the orbit of Neptune (at 30 AU) to approximately 50 AU from the Sun.

It is similar to the asteroid belt, although it is far larger — 20 times as wide and 20 to 200 times as massive. Like the asteroid belt, it consists mainly of small bodies, or remnants from the Solar System's formation.

While the asteroid belt is composed primarily of rock, ices, and metal, the Kuiper objects are composed largely of frozen volatiles (termed "ices"), such as methane, ammonia and water.

The classical (low-eccentricity) belt is home to at least three dwarf planets – Pluto, Haumea, and Makemake. Some of the Solar System's moons, such as Neptune's Triton and Saturn's Phoebe, are also believed to have originated in the region.

Hypotheses

Since the discovery of Pluto, many have speculated that it might not be alone. The region now called the Kuiper belt had been hypothesized in various forms for decades. The number and variety of prior speculations on the nature of the Kuiper belt have led to continued uncertainty as to who deserves credit for first proposing it.

In 1943, Kenneth Edgeworth hypothesized that, in the region beyond Neptune, the material within the primordial solar nebula was too widely spaced to condense into planets, and so rather condensed into a myriad of smaller bodies. From this he concluded that "the outer region of the solar system, beyond the orbits of the planets, is occupied by a very large number of comparatively small bodies" and that, from time to time, one of their number "wanders from its own sphere and appears as an occasional visitor to the inner solar system", becoming a comet.

In 1951, Gerard Kuiper speculated on a similar disc having formed early in the Solar System's evolution; however, he did not believe that such a belt still existed today. Kuiper was operating on the assumption common in his time, that Pluto was the size of the Earth, and had therefore scattered these bodies out toward the Oort cloud or out of the Solar System. Were Kuiper's hypothesis correct, there would not be a Kuiper belt where we now see it.

Discovery

In 1987, astronomer David Jewitt, then at MIT, became increasingly puzzled by "the apparent emptiness of the outer Solar System". He encouraged then-graduate student Jane Luu to aid him in his endeavour to locate another object beyond Pluto's orbit.

Using telescopes at the Kitt Peak National Observatory in Arizona and the Cerro Tololo Inter-American Observatory in Chile, Jewitt and Luu conducted their search in much the same way as Clyde Tombaugh and Charles Kowal had, with a blink comparator. The process was sped up with the arrival of electronic charge-coupled devices or CCDs.

Finally, after five years of searching, on August 30, 1992, Jewitt and Luu announced the "Discovery of the candidate Kuiper belt object" (15760) 1992 QB1. Six months later, they discovered a second object in the region, (181708) 1993 FW.

Exploration

After the New Horizons Spacecraft visit to the Pluto-Charon system in 2015, circumstances permitting, the spacecraft will continue on to study another as-yet undetermined Kuiper Belt Object. Who know what new discoveries await us?