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Pluto

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Pluto is a small world. It is far from the Sun. It is made of ice and rock. Pluto has five moons.

Nh-pluto moons family portrait.png
Nh-pluto moons family portrait.png
One moon is very big. It is called Charon. Do you like looking at the stars?

48 words

Pluto is a small world. It is far from the Sun. It is made of ice and rock.

Pluto has five moons.

Nh-pluto moons family portrait.png
Nh-pluto moons family portrait.png
One moon is named Charon. Charon is very big. It is about half the size of Pluto.

People found Pluto in 1930. A man named Clyde Tombaugh saw it. He looked at many pictures of the sky.

Pluto lives in a ring of objects. This ring is called the Kuiper belt. Many other small things live there too.

Scientists used to call Pluto a planet. Now they call it a dwarf planet. It is still a very special place.

111 words

Pluto is a small world in space. It lives in the Kuiper belt. This is a ring of objects far beyond Neptune. Pluto is made mostly of ice and rock. It is much smaller than the big planets.

Nh-pluto moons family portrait.png
Nh-pluto moons family portrait.png
Pluto has five known moons. The largest one is named Charon. Charon is very big. It is about half the size of Pluto. Because they are so large, they orbit each other in a special way.

Clyde Tombaugh found Pluto in 1930.

Pluto discovery plates.gif
Pluto discovery plates.gif
He looked at pairs of photos. He used a tool to see if objects moved. At first, people called Pluto the ninth planet. Later, scientists found many other objects in the Kuiper belt. They also found a large object named Eris. In 2006, experts changed the rules for what a planet is. Now, Pluto is called a dwarf planet. This means it is a small world that does not fit the old rules. A spacecraft named New Horizons visited Pluto in 2015. It took many close pictures of the icy world.

184 words

Pluto is a fascinating dwarf planet located in the Kuiper belt. This is a wide ring of many objects found far beyond the orbit of Neptune.

Outersolarsystem objectpositions labels comp.png
Outersolarsystem objectpositions labels comp.png
Pluto is a very small world compared to the big planets. It is the ninth-largest object to orbit the Sun directly. However, it is much less massive than the object named Eris. Pluto is mostly made of ice and rock. It has about one-sixth the mass of our Moon. It also has about one-third of the Moon's volume.
Nh-pluto moons family portrait.png
Nh-pluto moons family portrait.png

Pluto moves in a very specific way through space. Its orbit is shaped like an oval and is tilted. This is called an eccentric and inclined orbit.

Animation of Pluto orbit.gif
Animation of Pluto orbit.gif
Because of this path, Pluto sometimes gets closer to the Sun than Neptune does. A stable orbital resonance keeps Pluto and Neptune from hitting each other. It takes a long time for light to reach Pluto. Sunlight takes 5.5 hours to reach it.
Plutoorbit1.5sideview.gif
Plutoorbit1.5sideview.gif
Pluto also has five known moons. These are Charon, Styx, Nix, Kerberos, and Hydra.
Nh-pluto moons family portrait.png
Nh-pluto moons family portrait.png
Charon is the largest moon. It is so big that it is over half the diameter of Pluto.

Finding Pluto was a long journey for astronomers. In 1906, Percival Lowell began looking for a ninth planet. He called this mystery object "Planet X."

Clyde W. Tombaugh.jpeg
Clyde W. Tombaugh.jpeg
He used math to help find it. After he died, a young man named Clyde Tombaugh took over the search.
Pluto discovery plates.gif
Pluto discovery plates.gif
Tombaugh looked at pairs of photos to find moving objects. He used a tool called a blink comparator. This tool made objects look like they were moving. On February 18, 1930, he found a moving object. This object was Pluto.
Pluto discovery plates.gif
Pluto discovery plates.gif

People had many ideas for what to name the new world. An eleven-year-old girl named Venetia Burney suggested the name Pluto.

Pluto monogram (bold).svg
Pluto monogram (bold).svg
She liked the name from Roman mythology. The name was chosen because it was a unanimous vote.
Pluto symbol (large orb, bold).svg
Pluto symbol (large orb, bold).svg
Pluto was considered the ninth planet for a long time. But scientists later found many other objects in the Kuiper belt. They also found Eris in 2005. In 2006, the International Astronomical Union changed the rules. They decided Pluto is a dwarf planet.
Pluto symbol (southern Europe).svg
Pluto symbol (southern Europe).svg
Some astronomers still think Pluto should be a planet.

We know much more about Pluto thanks to space travel. A spacecraft named New Horizons visited Pluto in 2015. It flew by on July 14, 2015. This mission gave us detailed measurements and beautiful pictures. We can see that Pluto has icy mountains and flat plains.

MVIC sunset scan of Pluto.jpg
MVIC sunset scan of Pluto.jpg
Pluto and its moon Charon are very close. They orbit a point between them. This is called a barycenter.
Pluto-Charon system-new.gif
Pluto-Charon system-new.gif
Because they are tidally locked, they always face each other. This makes them look like a special pair in the dark sky.

536 words

Pluto is a dwarf planet located within the Kuiper belt. This is a vast ring of many celestial bodies orbiting far beyond the orbit of Neptune.

Outersolarsystem objectpositions labels comp.png
Outersolarsystem objectpositions labels comp.png
Pluto is the ninth-largest and tenth-most-massive object known to orbit the Sun directly. While it is the largest trans-Neptunian object by volume, it is less massive than the object Eris. Pluto is primarily composed of ice and rock. It is significantly smaller than the inner planets, possessing roughly one-sixth the mass and one-third the volume of Earth's Moon.

Pluto follows a complex path through the solar system. Its orbit is described as both eccentric and inclined. This means its path is an oval shape and is tilted relative to the plane of other planets.

Animation of Pluto orbit.gif
Animation of Pluto orbit.gif
Because of this eccentricity, Pluto periodically moves closer to the Sun than Neptune. However, a stable orbital resonance prevents any collision between the two bodies. Sunlight takes a long time to reach this distant world. It takes 5.5 hours for light to travel from the Sun to Pluto's orbital distance.
Plutoorbit1.5sideview.gif
Plutoorbit1.5sideview.gif

Pluto is accompanied by five known moons: Charon, Styx, Nix, Kerberos, and Hydra.

Nh-pluto moons family portrait.png
Nh-pluto moons family portrait.png
Charon is the largest of these moons. Its diameter is just over half that of Pluto. Because of their size and proximity, Pluto and Charon are often considered a binary system. They are tidally locked, meaning they always face one another. They actually orbit a common center of mass called a barycenter. This point of balance does not lie within either body.
Pluto-Charon system-new.gif
Pluto-Charon system-new.gif

Finding Pluto was the result of a long scientific search. In 1906, Percival Lowell began looking for a hypothetical ninth planet called "Planet X."

Clyde W. Tombaugh.jpeg
Clyde W. Tombaugh.jpeg
He used mathematical calculations to predict its location. After his death, Clyde Tombaugh took over the task at the Lowell Observatory.
Pluto discovery plates.gif
Pluto discovery plates.gif
Tombaugh used a blink comparator to examine pairs of photographic plates. This tool created an illusion of movement when shifting between views. On February 18, 1930, he identified a moving object. This discovery was confirmed through further observations and telegraphed to the Harvard College Observatory.

The naming of Pluto involved many suggestions from the public. An eleven-year-old girl named Venetia Burney suggested the name from classical mythology.

Pluto monogram (bold).svg
Pluto monogram (bold).svg
The name was chosen because it was a unanimous vote. It was mythologically appropriate because the god Pluto inhabited a dark region, much like the planet.
Pluto symbol (large orb, bold).svg
Pluto symbol (large orb, bold).svg
The name has since entered wider culture. For example, Walt Disney named his canine character Pluto after the planet. Additionally, the element plutonium was named after Pluto to follow the tradition of naming elements after planets.

Pluto's status as a planet has changed over time. For many years, it was considered the ninth planet. However, astronomers later discovered many other objects in the Kuiper belt. In 2005, the massive object Eris was discovered. This led the International Astronomical Union to redefine the term "planet" in 2006.

Pluto symbol (southern Europe).svg
Pluto symbol (southern Europe).svg
Under these new criteria, Pluto was reclassified as a dwarf planet. Despite this, many planetary astronomers still argue that Pluto should be considered a planet.

We have gained immense knowledge about Pluto through the New Horizons mission. This spacecraft performed a flyby on July 14, 2015. It provided the first detailed measurements and high-resolution images of the system. We learned that Pluto has complex features like icy mountains and flat plains.

MVIC sunset scan of Pluto.jpg
MVIC sunset scan of Pluto.jpg
Scientists also observed unique structures, such as a large area often called "Pluto's Heart." These observations helped scientists understand the composition and geology of this distant, icy world.

630 words
🖼️ Images & Media (24)
File:Pluto monogram (bold).svg
Pluto monogram (bold).svg
File:Pluto symbol (large orb, bold).svg
Pluto symbol (large orb, bold).svg
File:Pluto discovery plates.gif
Pluto discovery plates.gif
File:Clyde W. Tombaugh.jpeg
Clyde W. Tombaugh.jpeg
File:Pluto monogram (fixed width).svg
Pluto monogram (fixed width).svg
File:Pluto symbol (large orb, fixed width).svg
Pluto symbol (large orb, fixed width).svg
File:Pluto symbol (southern Europe).svg
Pluto symbol (southern Europe).svg
File:Pluto symbol (northern Europe).svg
Pluto symbol (northern Europe).svg
File:Pluto symbol (northern Europe, variant).svg
Pluto symbol (northern Europe, variant).svg
File:Charon symbol (fixed width).svg
Charon symbol (fixed width).svg
File:Animation of Pluto orbit.gif
Animation of Pluto orbit.gif
File:Plutoorbit1.5sideview.gif
Plutoorbit1.5sideview.gif

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