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056

Pluto

OLogy Series
place
card
056

Pluto

OLogy Series
place

Pluto was discovered in 1930 and considered to be the ninth planet in our solar system. Recently, its status has changed because it has less in common with the other eight planets than it does with similar objects in the Kuiper Belt, a band of cometary debris at the edge of our solar system. Pluto's a small piece of ice and rock, which makes it more similar to comets than to the other planets.

Pluto's structure most closely resembles that of:

Halley's Comet

an asteroid

Jupiter

Are you right?

Correct!

Pluto consists of a rocky core with ice around the outside. Since the discovery of Pluto, scientists have found many other objects beyond Neptune with similar compositions.

Neil Tyson, astrophysicist

The more we learned about Pluto, the more it failed to fit into any known planet classification scheme.

Pluto is much farther from the Sun than Neptune.

Fact
or
Fiction
?

Fiction

At some times Pluto is even closer to the Sun than its nearest planetary neighbor, Neptune. Its orbit is not round, like the planets, but much more oval.

It takes Pluto hundreds of Earth years to orbit the Sun.

Fact
or
Fiction
?

Fact

It takes 248 years, to be exact. Pluto's long, oddly-tilted orbit is much less circular than the planetary orbits.

Diameter: 1,400 miles
Location: orbits Sun just beyond Neptune
Average Distance from Sun: 3.7 billion miles
Average Surface Temperature: -370 degrees F
Orbital Period: 248 Earth years
Number of satellites: 1
Significance: largest object in the Kuiper Belt
Characteristics: a frozen ball of methane, nitrogen, and ice with a rocky core

Image credits: "Pluto: The Frozen Planet", R. Albrecht (ESA/ESO), Hubble Space Telescope, and NASA; Neil Tyson: AMNH.