Search results
Pluto was discovered in 1930 by Clyde W. Tombaugh, making it by far the first known object in the Kuiper belt.
- Pluto (Mythology)
1st century sculpture of Pluto in the Getty Villa. In...
- Moons of Pluto
The innermost and largest moon, Charon, was discovered by...
- Minor-Planet Designation
The major exception to the convention that the number tracks...
- Grand Tack Hypothesis
The "Mars problem" is a conflict between some simulations of...
- Scattered Disk
The scattered disc (or scattered disk) is a distant...
- Pluto (Disambiguation)
Pluto (), a character in Astro BoyPluto (Disney), a Disney...
- Pluto (Mythology)
People also ask
When was Pluto discovered?
Where is Pluto located?
Why was Pluto reclassified as a dwarf planet?
What was the first spacecraft to discover Pluto?
Discovered in 1930, Pluto was long considered our solar system's ninth planet. But after the discovery of similar worlds deeper in the Kuiper Belt, Pluto was reclassified as a dwarf planet in 2006 by the International Astronomical Union.
Feb 18, 2015 · Feb. 18, 1930: Pluto is first identified in photographs of the night sky.
Pluto was discovered in 1930 by Clyde Tombaugh at the Lowell Observatory in Arizona. It is a dwarf planet in the Kuiper Belt that was explored by NASA's New Horizons in 2015.
- Overview
- Basic astronomical data
In 2006 the International Astronomical Union (IAU) removed Pluto from the list of planets and classified it as a dwarf planet because of its small size, icy composition, and anomalous orbital characteristics. The IAU adopted this category to recognize the larger and more massive members with similar compositions and origins occupying the same orbital “neighborhood.”
Who discovered Pluto?
Amateur American astronomer Clyde Tombaugh found Pluto in the constellation Gemini on February 18, 1930.
How far is Pluto from Sun?
Pluto’s mean distance from the Sun is about 5.9 billion km (3.7 billion miles or 39.5 astronomical units).
Is Pluto's orbit circular or eccentric?
Pluto’s mean distance from the Sun, about 5.9 billion km (3.7 billion miles or 39.5 astronomical units), gives it an orbit larger than that of the outermost planet, Neptune. (One astronomical unit [AU] is the average distance from Earth to the Sun—about 150 million km [93 million miles].) Its orbit, compared with those of the planets, is atypical in several ways. It is more elongated, or eccentric, than any of the planetary orbits and more inclined (at 17.1°) to the ecliptic, the plane of Earth’s orbit, near which the orbits of most of the planets lie. In traveling its eccentric path around the Sun, Pluto varies in distance from 29.7 AU, at its closest point to the Sun (perihelion), to 49.5 AU, at its farthest point (aphelion). Because Neptune orbits in a nearly circular path at 30.1 AU, Pluto is for a small part of each revolution actually closer to the Sun than is Neptune. Nevertheless, the two bodies will never collide, because Pluto is locked in a stabilizing 3:2 resonance with Neptune; i.e., it completes two orbits around the Sun in exactly the time it takes Neptune to complete three. This gravitational interaction affects their orbits such that they can never pass closer than about 17 AU. The last time Pluto reached perihelion occurred in 1989; for about 10 years before that time and again afterward, Neptune was more distant than Pluto from the Sun.
Observations from Earth have revealed that Pluto’s brightness varies with a period of 6.3873 Earth days, which is now well established as its rotation period (sidereal day). Of the planets, only Mercury, with a rotation period of almost 59 days, and Venus, with 243 days, turn more slowly. Pluto’s axis of rotation is tilted at an angle of 120° from the perpendicular to the plane of its orbit, so that its north pole actually points 30° below the plane. (By convention, above the plane is taken to mean in the direction of Earth’s and the Sun’s north poles; below, in the opposite direction. For comparison, Earth’s north polar axis is tilted 23.5° away from the perpendicular, above its orbital plane.) Pluto thus rotates nearly on its side in a retrograde direction (opposite the direction of rotation of the Sun and most of the planets); an observer on its surface would see the Sun rise in the west and set in the east.
Students save 67%! Learn more about our special academic rate today.
Learn More
Mar 3, 2010 · Learn how Pluto, the ninth planet, was found by astronomer Clyde W. Tombaugh at the Lowell Observatory in Arizona. Discover why Pluto was demoted from planet status in 2006 and what makes it unique among the planets.
Discovered in 1930, Pluto was long considered our solar system's ninth planet. But after the discovery of similar intriguing worlds deeper in the distant Kuiper Belt, icy Pluto was reclassified as a dwarf planet.
