The ninth and most distant planet from the sun is no longer considered to be the largest known dwarf planet.

There are hundreds of thousands of rocky, icy bodies each larger than 62 miles (100 kilometers) across, as well as 1 trillion or more comets in the area.

When it was demoted to a dwarf planet in 2006 it caused a stir in the scientific community and among the general public.

There is a question about why isn't Pluto a planet.

There were strange deviations in the orbits of Neptune and Uranus, which led to the suggestion that there was a new planet called Pluto. There must be another who is tugging on the ice giants. In 1915,Lowell predicted the location of the mystery planet, but he died 15 years later. The discovery of the dwarf planet was based on predictions by other astronomer.

The new world got its name from the Roman god of the Underworld, according to the granddaughter of the man who named it. Her grandpa gave the name to the observatory. The initials are the first two letters of the dwarf planet.

What does Pluto look like?

Until 2015, little was known about the dwarf planet's size or surface conditions, since it is so far away. The diameter of the dwarf planet is less than one-fifth the diameter of Earth, and only two-thirds the diameter of the moon.

The mountains that reach as high as 11,000 feet are similar to the Rockies on Earth. Scientists think that the mountains are formed on a bedrock of water ice because methane and nitrogen ice are not strong enough.

The surface of Pluto is peppered with craters and a rugged landscape.

The surface of Pluto as seen from NASA's New Horizons during its July 2015 flyby. (Image credit: NASA/Johns Hopkins University Applied Physics Laboratory/Southwest Research Institute)
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The methane ice on the dwarf planet's surface is different from the ice on the other side. Astronomers found similar features to Earth's penitentes on the dwarf planet's ice ridge terrain. The Earth features are only a few meters in size, while the Pluto features are over one thousand feet tall.

The large heart-shaped region unofficially known as Tombaugh Regio is located on the surface of the dwarf planet. On the left side of the region, there is an area that looks like an ice cream cone. There are other variations in the composition of surface materials.

There is a region unofficially known as "Sputnik Planum" in the center of Tombaugh Regio. There are no craters caused by meteorite impacts in the area, suggesting that it is very young. There is a chance that this region is being shaped by geologic processes.

Dark streaks are a few miles long and are aligned in the same direction. It is possible that the lines are created by the winds.

NASA's Hubble Space Telescope has found evidence that Pluto's crust is made of complex organic molecule.

Photos of the dwarf planet and its moons.

One of the most frigid places in the solar system is the surface of the dwarf planet. The temperature here can be as low as minus 400 degrees. The pictures taken by the Hubble Space Telescope showed that the dwarf planet had grown more red over time.

Evidence is still out on whether or not Pluto had a ocean. If the ocean existed, it could have had a big impact on the history of the dwarf planet. The amount of ice in the zone of Sputnik Planitia was so heavy that it affected the orientation of the dwarf planet. Although looking at less likely scenarios, a thicker ice layer or movement in the rock could be responsible for the movement. Some scientists think that Pluto could have life if it had a liquid ocean.

What is Pluto made of?

NASA has some of the parameters of the dwarf planet.

Nitrogen and methane are the atmospheric compositions. The atmosphere of the dwarf planet can be seen as far as 1,000 miles above the surface.

The dwarf planet's small size and slow rotation suggest it doesn't have a magnetic field.

A mixture of 70 percent rock and 30 percent water ice is the chemical composition of the dwarf planet.

The dwarf planet has a rocky core surrounded by a mantle of water ice and more exotic ices such as methane, carbon monoxide and nitrogen ice.

Graphic illustrating the the surface, mantle and core of Pluto. A graphic of Pluto on the left shows Pluto's possible interior layers.

Infographic highlighting the surface, mantle and core properties of Pluto.  (Image credit: Future/Wikimedia Commons)
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Pluto's orbital characteristics

The distance from the sun to the moon is more than 50 times that of Earth. The distance from the sun to the dwarf planet can vary greatly since it is so eccentric. Calculating the distance from the sun to the dwarf planet is more difficult than calculating the distance from Neptune to the dwarf planet.

There are quick facts about the dwarf planet.

The solar system's other worlds have a different rotation than that of Pluto.

The average distance from the sun is over five million miles.

30.151 times that of Earth is how far away the perihelion is.

The distance from the sun is 4,538,698,000 miles.

In 1999, after 20 years as the eighth planet, in order to go out from the sun, Pluto crossed Neptune's path and became the farthest planet from the sun.

When Pluto is close to the sun, its surface ices thaw and form a thin atmosphere made of nitrogen and methane. This atmosphere is much higher in altitude than Earth's due to the fact that Pluto's gravity is less than Earth's. Most of the atmosphere of Pluto is thought to disappear when traveling farther away from the sun. In the time that it does have an atmosphere, there can be strong winds. Air flowing over mountains could explain the brightness variations in the atmosphere.

The atmosphere of Pluto is too thin to allow liquids to flow, but they may have streamed from the surface in the past. There was a frozen lake in Tombaugh Regio. The atmosphere on the planet could have been 40 times thicker than on Mars.

Artist's impression of NASA's New Horizons spacecraft

Artist's impression of NASA's New Horizons spacecraft. (Image credit: NASA/JHUAPL/SwRI)
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Scientists said they might have seen clouds in the atmosphere of the dwarf planet. There are seven bright features that are close to the terminator, which is where clouds form. The features are all low in altitude and are 888-609- 888-609- 888-609- 888-609- 888-609- Acetylene, ethane and hydrogen cyanide are likely to be found in these clouds.

Does Pluto have any moons?

Charon is the most distant of the five moons of the dwarf planet.

The astronomer discovered that the dwarf planet had a very large moon. The moon was named Charon after the demon whoferried souls to the Underworld.

Most planets and their moons have the same size as Charon and Pluto. Scientists refer to Pluto and Charon as double dwarf planets because of the fact that they lie between each other.

An image of Pluto in the foreground and Charon in the background.

A composite of enhanced color images of Charon (upper left) and Pluto (lower right), taken by NASA's New Horizons spacecraft on its 2015 flyby.  (Image credit: NASA/Johns Hopkins University Applied Physics Laboratory/Southwest Research Institute)
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The distance between London and Sydney is less than the distance between Pluto and Charon. One rotation of the dwarf planet takes 6.4 Earth-days. A phenomenon known as tidal locking occurs when Charon hovers over the same spot on the surface of Pluto.

Charon has a grayish tint. In the early days of the moon, the satellite probably could not support a ocean. The Pluto-Charon system is tipped on its side compared to the rest of the solar system.

There are canyons on the moon. The deepest part of those canyons goes down for 6 miles. There is a swatch of cliffs and troughs across the center of the satellite. The moon is covered in a darker material than the rest of the planet. Much of Charon's surface is free of craters like regions of Pluto. It was the first time that features like this have been seen in the belt. It is possible that the moon had its own version of plate tectonics.

In 2005, the Hubble Space Telescope was used to take pictures of the dwarf planet, which led to the discovery of two other small moons. The satellites are far away from Charon. It is estimated that Nix is 26 miles long and 20 miles wide, while Hydra is 55 miles long and 73 miles wide. Water ice is likely to be the main coating on the surface of Hydra.

The fourth moon was discovered in 2011. The larger part of the moon is around 8 km across, while the smaller part is around 5 km across. There was a fifth moon discovered on July 11, 2012 with an estimated width of 6 miles.

One of the leading hypotheses for the formation of Charon is that a small object hit a young Pluto. The idea is that most of the combined matter became Pluto. The collision that created Charon may have caused the other moons to form.

Missions to Pluto

The first probe to study the dwarf planet and its moons is from NASA. On July 14, 2015, it was the closest approach to the dwarf planet.

Some of the ashes of Pluto's discoverer, Clyde Tombaugh, can be seen in the picture.

Unprecedented dangers were created by the lack of knowledge of the Pluto system. Scientists were aware of the existence of only three moons around the dwarf planet. The idea of more satellites circling the dwarf planet, unseen from Earth, was spurred by the discovery of the two dwarf planets. There could have been serious damage if there had been a collision with unseen moons. Tools were put in place to protect the space probe during it's journey.

The first close-up images of the dwarf planet and its moons were returned in October of 2011.

Grainy black and white image showing a dark pluto surrounded by a

The the first close-up image of Pluto and one of it's moons. Pluto is surrounded by sunlight reflected from Charon.  (Image credit: NASA/Johns Hopkins APL/Southwest Research Institute/NOIRLab)
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Additional resources

NASA's 10 cool things we learned about Pluto can be explored in more detail. The developing landscape of our solar system can be found in the new tab. There are six things dwarf planets have taught us about the solar system.


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