A planet is a celestial body orbiting a star or stellar remnant that is massive enough to be rounded by its own gravity, is not massive enough to cause thermonuclear fusion, and has cleared its neighbouring region of planetesimals.The term planet is ancient, with ties to history, science,...
from the Sun
The Sun is the star at the center of the Solar System. It is almost perfectly spherical and consists of hot plasma interwoven with magnetic fields...
. It has the third-largest planetary radius and fourth-largest planetary mass in the Solar System
The Solar System consists of the Sun and the astronomical objects gravitationally bound in orbit around it, all of which formed from the collapse of a giant molecular cloud approximately 4.6 billion years ago. The vast majority of the system's mass is in the Sun...
. It is named after the ancient Greek deity of the sky Uranus
Uranus , was the primal Greek god personifying the sky. His equivalent in Roman mythology was Caelus. In Ancient Greek literature, according to Hesiod in his Theogony, Uranus or Father Sky was the son and husband of Gaia, Mother Earth...
, the father of Cronus
In Greek mythology, Cronus or Kronos was the leader and the youngest of the first generation of Titans, divine descendants of Gaia, the earth, and Uranus, the sky...
In ancient Roman religion and myth, Saturn was a major god presiding over agriculture and the harvest time. His reign was depicted as a Golden Age of abundance and peace by many Roman authors. In medieval times he was known as the Roman god of agriculture, justice and strength. He held a sickle in...
) and grandfather of Zeus
In the ancient Greek religion, Zeus was the "Father of Gods and men" who ruled the Olympians of Mount Olympus as a father ruled the family. He was the god of sky and thunder in Greek mythology. His Roman counterpart is Jupiter and his Etruscan counterpart is Tinia.Zeus was the child of Cronus...
In ancient Roman religion and myth, Jupiter or Jove is the king of the gods, and the god of the sky and thunder. He is the equivalent of Zeus in the Greek pantheon....
). Though it is visible to the naked eye like the five classical planets, it was never recognized as a planet by ancient observers because of its dimness and slow orbit.