It takes Earth years for Pluto to complete one orbit around the Sun. Its orbit is also more oval-shaped, or elliptical, than those of the planets. That means that sometimes Pluto is a lot nearer to the Sun than at other times, At times Pluto's orbit brings it closer to the Sun than Neptune.
Charon is about half the size of Pluto itself, making it the largest satellite relative to the planet it orbits in our solar system. Pluto and Charon are often referred to as a "double planet. Pluto is the only world so far named by an year-old girl.
In , Venetia Burney of Oxford, England, suggested to her grandfather that the new discovery be named for the Roman god of the underworld. He forwarded the name to the Lowell Observatory and it was selected. Pluto's moons are named for other mythological figures associated with the underworld. Charon is named for the river Styx boatman who ferries souls in the underworld as well as honoring Sharon, the wife of discoverer James Christy ; Nix is named for the mother of Charon, who is also the goddess of darkness and night; Hydra is named for the nine-headed serpent that guards the underworld; Kerberos is named after the three-headed dog of Greek mythology and called Fluffy in the Harry Potter novels , and Styx is named for the mythological river that separates the world of the living from the realm of the dead.
Pluto's place in mythology can get a little muddled, so we asked Dr. However, the Greek name "Plouton" from which the Romans derived their name "Pluto" was also occasionally used as an alternative name for Hades.
But Pluto is definitely the Roman spelling. The surface of Pluto is extremely cold, so it seems unlikely that life could exist there. At such cold temperatures, water, which is vital for life as we know it, is essentially rock-like. Pluto's interior is warmer, however, and some think there could even be an ocean deep inside.
If Earth was the size of a nickel, Pluto would be about as big as a popcorn kernel. From an average distance of 3. One astronomical unit abbreviated as AU , is the distance from the Sun to Earth. From this distance, it takes sunlight 5. There is a moment each day near sunset here on Earth when the light is the same brightness as midday on Pluto. Find out when you can experience "Pluto time" where you live. Pluto's orbit around the Sun is unusual compared to the planets: it's both elliptical and tilted.
Pluto's year-long, oval-shaped orbit can take it as far as One AU is the mean distance between Earth and the Sun: about 93 million miles or million kilometers. But on average, Pluto is 3. Since Pluto is so far from Earth , little was known about the dwarf planet's size or surface conditions until , when NASA's New Horizons space probe made a close flyby of Pluto. New Horizons showed that Pluto has a diameter of 1, miles 2, km , less than one-fifth the diameter of Earth, and only about two-thirds as wide as Earth's moon.
Observations of Pluto's surface by the New Horizons spacecraft revealed a variety of surface features , including mountains that reach as high as 11, feet 3, meters , comparable to the Rocky Mountains on Earth. While methane and nitrogen ice cover much of the surface of Pluto, these materials are not strong enough to support such enormous peaks, so scientists suspect that the mountains are formed on a bedrock of water ice.
Pluto's surface is also covered in an abundance of methane ice, but New Horizons scientists have observed significant differences in the way the ice reflects light across the dwarf planet's surface.
The dwarf planet also possesses ice ridge terrain that appears to look like a snakeskin; astronomers spotted similar features to Earth's penitentes, or erosion-formed features on mountainous terrain. The Pluto features are much larger; they are estimated at 1, feet m tall, while the Earth features are only a few meters in size. Another distinct feature on Pluto's surface is a large heart-shaped region known unofficially as Tombaugh Regio after Clyde Tombaugh; regio is Latin for region.
The left side of the region an area that takes on the shape of an ice cream cone is covered in carbon monoxide ice. Other variations in the composition of surface materials have been identified within the "heart" of Pluto. In the center left of Tombaugh Regio is a very smooth region unofficially known by the New Horizons team as "Sputnik Planum," after Earth's first artificial satellite, Sputnik.
This region of Pluto's surface lacks craters caused by meteorite impacts, suggesting that the area is, on a geologic timescale, very young — no more than million years old.
It's possible that this region is still being shaped and changed by geologic processes. These icy plains also display dark streaks that are a few miles long, and aligned in the same direction. It's possible the lines are created by harsh winds blowing across the dwarf planet's surface. Related: Photos of Pluto and its moons. Pluto's surface is one of the coldest places in the solar system, at roughly minus degrees Fahrenheit minus degrees Celsius.
When compared with past images, pictures of Pluto taken by the Hubble Space Telescope revealed that the dwarf planet had apparently grown redder over time, apparently due to seasonal changes.
Pluto may have or may have had a subsurface ocean, although the evidence is still out on that finding. If the subsurface ocean existed, it could have greatly affected Pluto's history. For example, scientists found that the zone of Sputnik Planitia redirected Pluto's orientation due to the amount of ice in the area, which was so heavy it affected Pluto overall; New Horizons estimated the ice is roughly 6 miles 10 km thick.
A subsurface ocean is the best explanation for the evidence, the researchers added, although looking at less likely scenarios, a thicker ice layer or movements in the rock may be responsible for the movement.
If Pluto did have a liquid ocean, and enough energy, some scientists think Pluto could harbor life. Therefore Eris is a dwarf planet. Q: What is an object called that is too small to be either a planet or dwarf planet? A: All objects that orbit the Sun that are too small not massive enough for their own gravity to pull them into a nearly spherical shape are now defined as being small Solar System bodies. Q: What is a small Solar System body? A: The term "small Solar System body" is a new IAU definition to encompass all objects orbiting the Sun that are too small not sufficiently massive to satisfy the definition of planet or dwarf planet.
Q: Is the term minor planet still to be used? A: The term "minor planet" may still be used. But generally the term small Solar System body will be preferred. Q: How will an official decision be reached on whether or not to call a newly discovered object a planet, dwarf planet, or a Solar System body? A: The decision on how to classify newly discovered objects will be made by a review committee within the IAU.
The review process will be an evaluation, based on the best available data, of whether or not the physical properties of the object satisfy the definitions.
It is likely that for many objects, several years may be required to gather sufficient data. Q: Are there additional planet candidates currently being considered? None appear likely in our Solar System. But there are planet discoveries galore around other stars.
Q: Are there additional dwarf planet candidates currently being considered? A: Yes. Some of the largest asteroids may be candidates for dwarf planet status and some additional dwarf planet candidates beyond Neptune will soon be considered. Q: When will additional new dwarf planets likely be announced? A: Probably within the next few years. Q: How many more new dwarf planets are there likely to be? A: There may be dozens or perhaps even more than a hundred waiting to be discovered.
Q: What are plutoids? A: Plutoids are celestial bodies in orbit around the Sun at a semimajor axis greater than that of Neptune that have sufficient mass for their self-gravity to overcome rigid body forces so that they assume a hydrostatic equilibrium near-spherical shape, and that have not cleared the neighbourhood around their orbit. Satellites of plutoids are not plutoids themselves, even if they are massive enough that their shape is dictated by self-gravity.
The two known and named plutoids are Pluto and Eris. It is expected that more plutoids will be named as science progresses and new discoveries are made. Read more. Q: Can a satellite orbiting a plutoid be a plutoid too? A: No, according to the IAU Resolution B5 a dwarf planet can not be a satellite, even if they are massive enough that their shape is dictated by self-gravity. Pluto and the Developing Landscape of Our Solar System The discovery of Pluto Nearly eighty years ago an astronomer working at the Lowell Observatory in the United States made a discovery that would ultimately initiate a dramatic change in the way we look at our Solar System.
As Professor Ron Ekers, past president of the IAU, explains: Such decisions and recommendations are not enforceable by any national or international law; rather they establish conventions that are meant to help our understanding of astronomical objects and processes. By the end of the Prague General Assembly, its members voted that the resolution B5 on the definition of a planet in the Solar System would be as follows: A celestial body that a is in orbit around the Sun, b has sufficient mass for its self-gravity to overcome rigid body forces so that it assumes a hydrostatic equilibrium nearly round shape, and c has cleared the neighbourhood around its orbit.
The latest observations On 14 July , NASA's New Horizons spacecraft flew past Pluto, providing numerous imaging, spectroscopy, and in situ datasets that have dramatically altered our knowledge about Pluto and its system of five moons. References: Stern, A.
Read more Q: Can a satellite orbiting a plutoid be a plutoid too? Read more References Brown, M.
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