The Truth Is Out There ...
At its closest to the sun, Pluto is still way beyond what could be seen with anything available by pre-1930. Astronomer Percival Lowell noticed deviations in the orbits of Uranus and Neptune. He theorized something was out there, and searched for Planet X from 1905, until his death in 1916, but never found it. Lowell had founded the Lowell Observatory in 1894, in Arizona. Thirteen years after his death, the Observatory dedicated a new 13-inch telescope to resume the hunt for Planet X. In 1929, they hired Clyde Tombaugh for the search. After a year of intensive, painstaking work, Planet X was discovered in February 1930 -Tombaugh thought he’d found a 9th planet. The Observatory verified his observations, & on what was Lowell’s birthday, 13 March 1930, they announced it to the world. Planet X was named “Pluto”, keeping the tradition of old god names (Pluto was the god of the dead, reigning over Hades, or Hell, which they thought Pluto’s surface would be. It also had the initials of Perceval Lowell -PL - as the first 2 letters.)
Pluto is usually the farthest from the sun, but, if you look at the orbit of Neptune, you will see an overlap within Pluto’s orbit. A Pluto year is equal to 248 Earth years. A day on Pluto is 6.4 Earth days. Astronomers kept studying Pluto, noting anomalies - the moon discovered in 1978, named Charon (the Greek ferryman who took souls to Hades), was very large in comparison to other planet/moon combinations. It’s orbit is the only one that crosses another planet’s orbit. It’s the smallest “planet” - even smaller than little Mercury. Other large bodies were found as beyond Neptune as the telescopes increased in size & power. Finally, in 2006, the International Astronomical Union (IAU), made of list of requirements to be a planet, & Pluto was downgraded to a dwarf planet. Poor Pluto. Oh, the humanity! Pluto & Charon are thought to be a binary system. Pluto has 5 known moons, including Charon.
So now we have Pluto, feted as the newest planet, thrown out like old dish water. Poor baby. But Pluto doesn’t care! It just keeps going on it’s eccentric orbit, somehow missing Neptune when the orbits overlap. (The article tried to S’plain it to me - I’ll just go with Magic. Now on to the Kuiper Belt (also called the Edgewood-Kuiper Belt after the 2 astronomers who postulated it’s existence.) While Pluto was still considered a planet, astronomers had theorized on more small planets, debris, etc. They nailed it, eventually (1992) finding proof of the “belt” beyond Neptune, like the inner belt between Mars & Jupiter. For both of the belts, they are thought to be created out of left-over remnants of from the formation of the Solar System’s creation. The theory is the small bits don’t have enough gravity to built planets. The Kuiper belt is found between Neptune’s orbit of 30 AU to 50 AU. Oh, I forgot to explain AU, or astronomical unit. It is a unit of measurement equal to 149.6 million kilometers, the mean distance from the center of the earth to the center of the sun. Much easier to describe the HUGE distances as 30 AU instead of 4,488, 000,000 kilometers. Makes my head hurt with numbers so large.
So now the K-belt (I’m tired of typing the whole thing) i s known to harbor the short-term comets - those that return in less to 200 years to swing around the sun. Every time they swing in towards the sun, some of the ice melts & makes the comet & tail visible. Of course, that means every time it swings by, it gets a little smaller. There are 2 types of short period comets - “A comet with an orbital period of less than 200 years is known as a short-period comet or a ‘periodic comet’. These are now divided into Jupiter-family comets with periods less than 20 years and orbits that do not extend much beyond Jupiter, and Halley-type comets with periods of 20–200 years and highly inclined orbits“. (from Cosmos.) Halley’s Comet appears every 75-76 years. It’s due back in 2061-62. Long-period comets orbit over 200 years & come from the Oort Cloud (even further out!)