The Solar System contains eight planets, which orbit the Sun at increasing distances. The planet positioned second farthest from the Sun is Uranus. Directly following Uranus is Neptune, the eighth and most distant planet.
The Official Planetary Sequence
The order of the eight major planets, moving outward from the Sun, is Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, and Neptune. This sequence is maintained by the International Astronomical Union (IAU). The IAU established a formal definition for a planet in 2006, which solidified the current eight-planet model.
The designation of Uranus as the second farthest planet is a direct consequence of Neptune being the farthest. The orbit of Neptune is the last major planetary orbit before the region of dwarf planets and numerous small icy bodies begins. Neptune’s average orbital path is roughly 30 Astronomical Units (AU) from the Sun, where one AU is the Earth-Sun distance. Uranus orbits at approximately 19 AU, illustrating the wide gulfs of space in the outer solar system.
Neptune: The Farthest World
Neptune is classified as an Ice Giant, a category it shares with its inner neighbor. Its deep blue color is primarily due to the absorption of red light by methane gas high in its atmosphere. Below this layer, the planet is composed of a dense, hot fluid mixture of water, methane, and ammonia ices surrounding a smaller, solid core.
The conditions on the farthest planet are extreme, featuring the fastest winds recorded in the Solar System, reaching 1,200 miles per hour. Due to its immense distance from the Sun, Neptune takes approximately 165 Earth years to complete a single orbit. Since its discovery in 1846, it only finished its first complete solar orbit in 2011.
Why Pluto is Not Included
The confusion over which planet is second farthest often stems from the historical inclusion of Pluto, which was once considered the ninth and most distant planet. However, in 2006, the IAU formally reclassified Pluto as a dwarf planet, removing it from the major planetary sequence. This decision was based on three specific criteria that a celestial body must meet to be considered a full planet.
A body must orbit the Sun, have sufficient mass to assume a nearly round shape, and, crucially, it must have cleared the neighborhood around its orbit. Pluto fails this final criterion because its orbit is shared with thousands of other large icy bodies within the Kuiper Belt. Pluto is just one of the largest objects in this vast, disk-shaped region beyond Neptune. The existence of these other large objects shows that Pluto does not gravitationally dominate its orbital zone, which is why the farthest official planet remains Neptune.