Discovery
In the 1840s, Urbain Le Verrier used Newtonian mechanics to predict the position of the then-undiscovered planet Neptune after … See more

Pluto's orbital period is about 248 years. Its orbital characteristics are substantially different from those of the planets, which follow nearly circular orbits around the Sun close to a flat reference plane called the ecliptic. In contrast, Pluto's orbit is moderately See more

Pluto's diameter is 2376.6±3.2 km and its mass is (1.303±0.003)×10 kg, 17.7% that of the Moon (0.22% that of Earth). Its surface area is 1.774443×10 km , or just slightly bigger than … See more

Pluto has five known natural satellites. The largest and closest to Pluto is Charon. First identified in 1978 by astronomer James Christy, … See more

Pluto's rotation period, its day, is equal to 6.387 Earth days. Like Uranus and 2 Pallas, Pluto rotates on its "side" in its orbital plane, with an axial tilt of 120°, and so its seasonal variation is extreme; at its solstices, one-fourth of its surface is in continuous … See more

Surface
The plains on Pluto's surface are composed of more than 98 percent nitrogen ice, with traces of methane and carbon monoxide See more

Pluto has a tenuous atmosphere consisting of nitrogen (N2), methane (CH4), and carbon monoxide (CO), which are in equilibrium with their ices on Pluto's surface. According to … See more