The planet is Pluto was known as the farthest planet from the sun till 2006. It no longer has that title. Now called a dwarf planet, it is no longer classified as a planet.
It is so far from the sun, our solar system’s source of heat, that even on a “summer” day Pluto is horribly cold, minus 400 degrees F. Even at “high noon,” daylight is so weak it is almost impossible to see anything.
Pluto has half the gravity of earth, which means that you could throw a ball twice as far, jump twice as high, and carry twice the load you can on your home planet. Pluto wasn’t discovered until 1930, because even through very powerful telescopes, the planet looks like a very pale point of yellow light.
More will be learned about Pluto when the space shuttle enables us to build a telescope in outer space.
It is now widely accepted that Neptune is the farthest planet in the solar system from the Sun.