1. As of 2006, Pluto is not longer considered a planet, but rather designated as a “dwarf planet,” meaning that it is a planetary-mass object being neither a planet nor a satellite. Pluto was declassified as a planet by the International Astronomical Union (IAU). 2. Pluto is the smallest dwarf planet in the Solar System, smaller than Earth’s Moon, and half the width of Jupiter’s moon, Ganymede. 3. Pluto’s journey around the Sun takes 248 Earth years. This means that, since its discovery in 1930, it still has over 160 years to go until it has made a complete orbit around the Sun. 4. Pluto’s atmosphere is composed of a thin layer of gas containing carbon monoxide, methane, and nitrogen. Its atmospheric pressure has been estimated to be 1/700,000 compared with that of earth. 5. Pluto orbits the Sun on a different plane than the 8 planets, going over them and below them. 6. Pluto has four identified moons, Charon, the largest is not much smaller than Pluto itself. (Pluto is 2,280 kilometers wide, Charon is 1,212 kilometers wide). The other 3 are Nix, Hydra, and newly discovered S/2011 P 1 on July of 2011. 7. A day on Pluto is equivalent to Earth’s 6 days and 9 hours, meaning that it has the second slowest rotation in the Solar System (after Venus, which takes 243 days to turn on its axis). 8. Pluto’s orbit is elliptical, meaning that it can come closer to the Sun than Neptune, but then go almost two billion kilometers further away from Neptune’s orbit. 9. Pluto is too faint to be seen with the naked eye. When viewed through a telescope, it looks like a star. 10. Pluto is cold: -233° C (-390° F), just 40° C (72° F) above absolute zero. At this temperature, all elements would be frozen except for neon, hydrogen, and helium. 11. Pluto maximum distance from the Sun – 7.38 billion km (4.6 billion miles). 12. Pluto’s minimum distance from Earth – 4.28 billion km (2.7 billion miles). 13. If you weigh 100 lbs, your weight on Pluto would be 7 lbs. (multiply your actual weight by .067). 14. When gazing at the Sun from Pluto it would appear as a tiny bright start because the two are so far away from each other. 15. According to some astronomers, Pluto used to be one of Neptune’s moons, but it somehow broke out of its orbit. 16. Pluto was first located by Clyde Tombaugh in 1930. 17. One of the reasons why Pluto was declassified as a planet was because there are asteroids in the solar system that are bigger than Pluto. 18. Since being declassified as a planet, Pluto’s technical name is now 134340.
Pluto Facts - The Planet Pluto
Pluto was first seen by use of a telescope in 1930. Like Uranusand Neptune, Pluto can not be seen by the naked eye and its existence was not known to the ancient world. In 1930 the discovery of Pluto by Clyde Tombaughin the Lowell Observatory was heralded as the discovery of the “ninth planet”.Even in 1930, however, many astronomers did not agree that a ninth planet had been discovered. In 2005 another possible planet, Eris, was found beyond Neptune, the eighth planet and since then 2 further small planet-like bodies have been discovered. These bodies are unlike the other planets in the Solar system. The first eight planets orbit the Sunin a path which they have cleared of other objects. Pluto, however, orbits the sun in a zone which is full of other objects that often pass between Pluto and the Sun. The first eight planets orbit the Sun while keeping the same distance from the Sun. The Earth is always 93 million miles, one Astronomical Unit, from the Sun. Pluto, however, orbits in an ellipse, an oval shape which means its distance from the Sun varies. See figure 2. In 2006 the International Astronomical Union agreed that these “planets” should be called “dwarf planets”. Pluto was the Roman God of the Underworld. Of the nine planets which most people think of as being in the Solar system, Pluto is the 2nd smallest, only just bigger than Mercury. We know very little about Pluto. The US National Aeronautics and Space Administration (NASA) has sent the unmanned spacecraft New Horizonsto Pluto. New Horizons left the Earth in 2005 but will not reach Pluto until 2015. Pluto is probably even smaller than Mercury, with a diameter of around 1400 miles (about 2240 kilometres). It takes Pluto 248½ years to complete its orbit round the Sun. The Earth takes one year. Like all the planets Pluto turns on its own axis as it orbits round the sun. Pluto takes about 6½ days to turn on its axis. The Earth takes 24 hours, one day. Figure 1: A NASA photograph of Pluto and its four moons. Charon is the closest. Since Pluto was the Roman God of the Underworld, the planet’s main moon, Charon, is named after the ferryman who carries the dead souls across the River Styx into the Underworld. Pluto is known to have four moons, shown in Figure 2. Pluto’s distance from the Sun varies. Since the planet was only discovered in 1930 and it takes 249 years to orbit the Sun, a full orbit has not been observed. From calculations astronomers have worked out that Pluto’s orbit round the sun is not regular. The orbit is tilted when compared to the orbits of the other eight planets, as shown in Figure 3. Figure 2: The Planets’ Orbits round the Sun, showing Pluto’s unusual orbit. In this diagram, produced by the BBC, you can see that at some points in Pluto’s orbit the planet will be closer to the Sun than Uranus and Neptune, the seventh and eighth planets. Between 1979 and 1999 Pluto was closer to the Sun than the planet Neptune, moving inside Neptune’s orbit. Distances in astronomy are measured in Astronomical Units, with the Earth’s distance from the Sun being taken as one Astronomical Unit (1AU). The photograph in Figure 2 was taken in 1994 by the Hubble Space Telescope. Pluto was about 30 AUs from the Sun, approximately 2796 million miles, or 4500 million kilometres. However, during its long 248 year orbit round the Sun, Pluto will move as far as 49 AUs from the Sun – the position which is shown in Figure 2.Useful Website Why Plutois not a planet anymore Nice information about Pluto Alternate Images of Pluto
Pluto: 9 Facts You Need to Know
With discoveries about Pluto from NASA’s New Horizons mission rolling in, here are nine of the most interesting facts about the former planet. 1. Pluto was first discovered by a young research assistant in 1930 Photographic evidence of the former ninth planet was first sighted by 24-year-old research assistant Clyde Tombaugh at the Lowell Observatory in Flagstaff, Ariz. Tombaugh’s ashesare aboard the New Horizons spacecraft that passed by Pluto on Tuesday. Astronomer Percival Lowell predicted Pluto’s existence 15 years prior to Tombaugh’s discovery–even charting its approximate location based on the irregularity of Neptune’s orbit. 2. An 11-year-old girl gave Pluto its name When Venetia Burney’sgrandfather told her the news of the newly discovered planet, she proposed the name Pluto, after the Roman god of the Underworld. It seemed fitting, for after all, Pluto the planet, like the God, sat at the far reaches of the solar system. Her grandfather was taken by the name and suggested it to a friend–conveniently an astronomy professor at Oxford University. Astronomers were particularly keen on Pluto because the first two letters of the word are Percival Lowell’s initials.
Facts About the Planet Jupiter: Fun/Interesting Information on Jupiter
1. Jupiter is the largest planetin our solar system with a mean diameter of 139,822 km (86,881 miles). 2. Jupiter’s mass is 318 times larger than Earth. The diameter is 11 times, volume is 1,321 times, and surface area is 122 times of Earth. 3. The orbital speed of Jupiter is 13.1 km/sec. 4. A year on Jupiter is equal to 11.9 Earth Years. 5. A day on Jupiter is equal to 9.8 Earth Hours. 6. Jupiter, sometimes called Jove, was the King of the gods in Roman mythology and the son of Saturn. 7. Jupiter’s maximum distance from the Sun = 817 million km (508 million miles). 8. Jupiter’s minimum distance from Earth = 588 million km (365 million miles). 9. Pioneer 10 was the first spacecraft to explore Jupiter in December 1973. Pioneer 10 just did a flyby. 10. Jupiter has sixty three moons or satellites, eight are regular and 55 irregular. 11. Jupiter’s four largest moons are named: Io, Europa, Ganymede, and Callisto. 12. Voyager 1 provided the earliest and clearest photographs of Jupiter on January of 1979. 13. Jupiter has rings, the third planet discovered to have a ring system in our Solar System. 14. Jupiter’s rings are identified as: Halo ring, Main ring, Amalthea gossamer ring, and Thebe gossamer ring. 15. Jupiter’s rings were discovered by Voyager 1 in 1979. 16. If you weigh 100 lbs, your weight on Jupiter would be 236 lbs. (multiply your actual weight by 2.36). 17. The volume of Jupiter is great enough to hold 1,300 Earths. 18. The rotation of Jupiter is the fastest of any planet in the Solar System, making its days only 10 hours long. 19. The large red spot on Jupiter is actually from a storm that has lasted over 300 years. 20. Jupiter’s largest moon is the biggest in the Solar System. Named Ganymede, it is larger than the planet Mercury.
Welcome to a site filled with fun planet facts on all the planets of our Solar SystemThere are eight planets that orbits the Sun: Mercury, Venus, Mars, Earth, Jupiter, Saturn, Uranus and Neptune. On this site, each planet has its own facts page, with interesting and little known facts about each planet. Pluto has its own facts page too, even though it has been declassified as a planet.Select Which Planet Facts Page You want to See: MercuryThe closest planet to the Sun VenusA beautiful looking planet with a deadly atmosphere EarthOur home planet MarsThe Martian planet JupiterThe Biggest planet in our Solar System SaturnKnown for its beautiful rings UranusAn upside down world NeptuneThe Blue Icy Wonder PlutoThe former planet
Dwarf Planet Pluto
Dwarf Planet PlutoCome wander with me, she said,Into regions yet untrod;And read what is still unreadIn the manuscripts of God. - LongfellowCopyright © 1998-2015 by Rosanna L. Hamilton. All rights reserved.
Pluto orbits beyond the orbit of Neptune (usually). It is much smaller than any of the official planets and now classified as a "dwarf planet".Pluto is smallerthan seven of the
Pluto FactsPluto is the second closest dwarf planetto the Sunand from 1930 when it was discovered up until 2006, it was also considered the ninth planetof the solar system. It is also the second largest dwarf planet, with Erisbeing the most massive known dwarf planet. On July 14, 2015, The New Horizons mission did a Pluto flyby to capture the first high resolution photographs of the planet and gather incredible data on Pluto and its worlds. Size of Pluto compared to the EarthSide by side comparison of the size of Pluto vs EarthThe moons of PlutoSide by side size comparison of pluto and its five known moonsPluto has 5 known moons. In order of distance from Pluto, these are Charon, Styx, Nix, Kerberos and Hydra. Charon is the largest of the moons and mutually tidally locked with Pluto. This is a gravitational lock that makes one side of an astronomical body always face the another – for example how the same side of the Moonalways faces Earth. Charon hovers over the same spot on Pluto – and the same side of Charon always faces Pluto. Charon is also so large that Pluto-Charon are sometimes considered a double object, a double dwarf planet or a binary system. Facts about PlutoPluto was discovered on February 18th, 1930 by Clyde Tombaugh of the Lowell Observatory. In the 76 years between its discovery and subsequent reclassification as a dwarf planet, the planet completed under one third of its orbit around the Sun.In 2006, Pluto was reclassified from a planet to a dwarf planet. This happened after the IAU formalised the definition of a planet as “A planet is 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 planet is named for Pluto, the Roman god of the underworld – the Roman alternative for the Greek god Hades. The name was proposed by an eleven year-old schoolgirl from Oxford, England by the name of Venetia Burney.It takes Pluto 246.04 Earth years to orbit the Sun.Pluto has five known moons. These are Charon, Styx, Nix, Kerberos and Hydra. The latter two moons were known as S/2011 (134340) 1 and S/2012 (134340) 1 before they were officially named.Pluto is smaller than many moons. When it was first discovered, Pluto’s small size surprised the scientific community who predicted it would be as large as Jupiter. The moons Ganymede, Titan, Callisto, Io, Europa, Triton, and the Earth’s moonare all larger than Pluto. It has 66% of the Moon’s diameter and just 18% of its mass.Sunlight on Pluto has the same intensity as moonlight on Earth. This is because it located so far from the Sun in the outer solar system – approximately 5,945,900,000 km.Either Pluto or Eris is the largest dwarf planet. The most accurate measurements currently put Eris at an average diameter of 2,326 km with a 12 km margin of error, compared to a 2,368 km diameter with a 20 km margin of error for Pluto. The atmosphere on Pluto makes it difficult to accurately map its size.The orbit of Pluto is eccentric and inclined. This means that the orbit takes it anywhere from 4.4 to 7.4 km from the Sun and that periodically Pluto is actually close to the Sun than the eight planet, Neptune.The first spacecraft will visit Pluto in July 2015. The New Horizons mission, launched in 2006 did a Pluto flyby on July 14th, 2015, on its way to the distant Kuiper Belt after almost a decade of flight.The term “plutoid” is used to describe objects in the solar system that are rounded and orbit the Sun beyond the orbit of Neptune. There are currently only four recognized plutoids – Pluto, Eris, Haumea and Makemake. Some astronomers believe they are at least 70 more objects that could be plutoids and are awaiting classification.Pluto and its moon Charon form a binary system. This means that the center of mass of the two objects is outside of Pluto and Pluto moves in small circles while Charon orbits it.The orbit of Pluto is chaotic and unpredictable. Scientists are able to predict the location of Pluto along its orbit path for the next 10-20 million years – beyond that it is unknown.It took sunlight over 3 hours to reach the New Horizons mission flying to Pluto.Some of the ashes of Clyde Tombaugh, the astronomer who discovered Pluto, are onboard the New Horizons probe that went to Pluto and beyond.Scientists believe that Pluto is made up of 50–70% rock and 30–50% ice by mass.Pluto is expected to have a solid rocky core, surrounded by a water ice mantle and a frozen nitrogen surface.Pluto’s core is predicted to be around 70% of its total diameter. This would put the core at around 1,700 km in diameter (1,000 miles).Pluto has an atmosphere sometimes. When Pluto is closer to the Sun on its elliptical orbit path the surface ice thaws and forms a thin atmosphere of nitrogen, methane and carbon monoxide. As it travels away from the Sun this then freezes back into its solid state.The history of PlutoPluto is a dwarf planet that was discovered in 1930 by Clyde Tombaugh, who at the time was working at the Lowell Observatory in Flagstaff, Arizona. Tombaugh discovered Pluto accidentally while looking for an unknown planet called Planet X that was causing disturbances in the orbits of Uranusand Neptune. By comparing two photographs of the night sky taken one week apart, he noticed an unknown faint spot that had possibly moved. Photographs obtained later confirmed the moving object and after receiving suggestions for the new planet’s name from around the world, the name Pluto was announced on May 1, 1930. Later observations of Pluto however showed that it was not the Planet X that astronomers were looking for. In fact, it was later shown that Planet X did not really exist. Pluto lies within a disc-shaped zone beyond Neptune’s orbit populated by tiny icy objects. This region is called the Kuiper Beltand its inhabitants are referred to as Kuiper Belt objects or trans-Neptunian objects. But in recognition of Pluto’s special place in astronomical history when it was downgraded to a dwarf planet, objects found in this region are also called “plutoids”. This icy region is believed to have formed in the early evolution of the Solar System. Not all plutoids are tiny. Eris, another dwarf planet, is actually more massive than Pluto. Because of its distance, it is difficult to determine what Pluto is made of. But it is believed to be composed of a rocky core, a mantle of water ice and a surface covered with methane ice and frosty nitrogen. Although Pluto is the second largest dwarf planet in the Solar System (after Eris), its diameter of 2,302 km (1430.4 mi) is only two-thirds that of the Earth’s moon. It has a mass of 1.31 x 1022 kg, which is one-sixth that of the moon. Pluto is smaller than Jupiter’sfour largest moons (Io, Ganymede, Europa and Callisto) and the largest moons of Saturn (Titan) and Neptune (Triton). Pluto’s orbit around the Sun takes 246.02 Earth years. Unlike the eight planets in the Solar System, which have a more or less circular and flat orbit, the dwarf planet’s orbit is elliptical and highly inclined, similar to the dwarf planet Eris. Its perihelion brings it 4.44 x 109 km (2.76 x 106 mi) closer to the Sun, but this is 30 times farther than the Earth is to the Sun. Its aphelion takes it 7.37612 x 109 km (4.58 x 109 mi) away from the Sun, which is 48 times the Earth’s aphelion. When Pluto is close to the Sun, its icy surface melts, rises and forms a thin layer of gaseous atmosphere comprised of nitrogen, methane and carbon monoxide. As the dwarf planet moves farther away, this atmosphere freezes and falls back to the surface. Pluto completes one rotation in 6.39 Earth days. Its rotation is retrograde, meaning it rotates from east to west like the planets Uranus and Venus. Because it has an axial tilt of 122.5°, it actually rotates on its side. This creates extreme variations in its seasons. In 1978, almost 50 years after Pluto’s discovery, the first moon orbiting the dwarf planet was discovered. Charon is nearly half of Pluto’s size and orbits 19,640 km (12,200 mi) away from it. Photographs taken of these two bodies show that Charon is gray, whereas Pluto is red. This indicates that their surfaces are composed of different materials. In 2005, the Hubble Space Telescope discovered two additional moons orbiting Pluto, which were named Nix and Hydra. These two moons’ orbits are farther away from the dwarf planet than Charon. In 2011 and 2012, two more moons were discovered by Hubble and they are temporarily named P4 and P5. The United States National Aeronautics and Space Administration (NASA) launched the spacecraft mission New Horizons in 2005 to study Pluto and the other icy objects in the Kuiper Belt. It arrived on a Pluto flyby on July 14th, 2015 after a nine year trip. Search The Universe
Pluto: Facts & Information About the Dwarf Planet Pluto
Pluto, once considered the ninth and most distant planet from the sun, is now the largest known dwarf planet in the solar system. It is also one of the largest known members of the Kuiper Belt, a shadowy zone beyond the orbit of Neptune thought to be populated by hundreds of thousands of rocky, icy bodies each larger than 62 miles (100 kilometers) across, along with 1 trillion or more comets. In 2006, Pluto was reclassified as a dwarf planet, a change widely thought of as a demotion. The question of Pluto's planet status has attracted controversyand stirred debatein the scientific community, and among the general public, since then. In 2017, a science group (including members of the New Horizon mission) proposed a new definition of planethoodbased on "round objects in space smaller than stars," which would make the number of planets in our solar system expand from 8 to roughly 100. American astronomer Percival Lowellfirst caught hints of Pluto's existence in 1905 from odd deviations he observed in the orbits of Neptune and Uranus, suggesting that another world's gravity was tugging at these two planets from beyond. Lowell predicted the mystery planet's location in 1915, but died without finding it. Pluto was finally discovered in 1930 by Clyde Tombaughat the Lowell Observatory, based on predictions by Lowell and other astronomers. Pluto got its name from 11-year-old Venetia Burney of Oxford, England, who suggested to her grandfather that the new world get its name from the Roman god of the underworld. Her grandfather then passed the name on to Lowell Observatory. The name also honors Percival Lowell, whose initials are the first two letters of Pluto. Physical characteristicsSince Pluto is so far from Earth, little was known about the dwarf planet's sizeor surface conditions until 2015, when NASA's New Horizons space probe made a close flyby of Pluto. New Horizons showed that Pluto has a diameter of 1,473 miles (2,370 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 11,000 feet (3,500 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. [Photos of Pluto and Its Moons] 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 terrainthat 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 1,650 feet (500 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 100 million years old. It's possible that this region is still being shaped and changed by geologic processes. These icy plains also display dark streaksthat 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. NASA's Hubble Space Telescope has also revealed evidence that Pluto's crust could contain complex organic molecules. Pluto's surface is one of the coldest places in the solar system, at roughly minus 375 degrees Fahrenheit (minus 225 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 oceanis 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. Orbital characteristicsPluto's highly elliptical orbit can take it more than 49 times as far out from the sun as Earth. Since the dwarf planet's orbit is so eccentric, or far from circular, Pluto's distance from the suncan vary considerably. The dwarf planet actually gets closer to the sun than Neptune is for 20 years out of Pluto's 248-Earth-years-long orbit, providing astronomers a rare chance to study this small, cold, distant world. As a result of that orbit, after 20 years as the eighth planet (in order going out from the sun), in 1999, Pluto crossed Neptune's orbit to become the farthest planet from the sun (until it was demoted to the status of dwarf planet). When Pluto is closer to the sun, its surface ices thaw and temporarily form a thin atmosphere, consisting mostly of nitrogen, with some methane. Pluto's low gravity, which is a little more than one-twentieth that of Earth's, causes this atmosphere to extend much higher in altitude than Earth's. When traveling farther away from the sun, most of Pluto's atmosphereis thought to freeze and all but disappear. Still, in the time that it does have an atmosphere, Pluto can apparently experience strong winds. The atmosphere also has brightness variationsthat could be explained by gravity waves, or air flowing over mountains. While Pluto's atmosphere is too thin to allow liquids to flow today, they may have streamed along the surface in the ancient past. New Horizons imaged a frozen lake in Tombaugh Regiothat appeared to have ancient channels nearby. At some point in the ancient past, the planet could have had an atmosphere roughly 40 times thicker than on Mars. In 2016, scientists announced that they might have spotted clouds in Pluto's atmosphereusing New Horizons data. Investigators saw seven bright features that are near the terminator (the boundary between daylight and darkness), which is commonly where clouds form. The features are all low in altitude and roughly about the same size, indicating that these are separate features. The composition of these clouds, if they are indeed clouds, would likely be acetylene, ethane and hydrogen cyanide. A close-up view of the surface of Pluto, taken by the New Horizons space probe in July, 2015, revealed the presence of icy mountains on the dwarf planet's surface. (Image: © NASA-JHUAPL-SwRI)Composition & structureSome of Pluto's parameters, according to NASA: Atmospheric composition: Methane, nitrogen. Observations by New Horizons show that Pluto's atmosphere extends as far as 1,000 miles (1,600 km) above the surface of the dwarf planet. Magnetic field: It remains unknown whether Pluto has a magnetic field, but the dwarf planet's small size and slow rotation suggest it has little to no such field. Chemical composition: Pluto probably consists of a mixture of 70 percent rock and 30 percent water ice. Internal structure: The dwarf planet probably has a rocky coresurrounded by a mantle of water ice, with more exotic ices such as methane, carbon monoxide and nitrogen ice coating the surface. (Image: © Karl Tate, SPACE.com)Orbit & rotationPluto's rotation is retrograde compared to the solar systems' other worlds; it spins backward, from east to west. Average distance from the sun: 3,670,050,000 miles (5,906,380,000 km) — 39.482 times that of Earth Perihelion (closest approach to the sun): 2,756,902,000 miles (4,436,820,000 km) — 30.171 times that of Earth Aphelion (farthest distance from the sun): 4,583,190,000 miles (7,375,930,000 km) — 48.481 times that of Earth Pluto's moonsPluto has five moons: Charon, Styx, Nix, Kerberos and Hydra, with Charon being the closest to Pluto and Hydra the most distant. In 1978, astronomers discovered that Pluto had a very large moonnearly half the dwarf planet's own size. This moon was dubbed Charon, after the mythological demon who ferried souls to the underworld in Greek mythology. Because Charon and Pluto are so similar in size, their orbit is unlike that of most planets and their moons. Both Pluto and Charon orbit a point in space that lies between them, similar to the orbits of binary star systems, For this reason, scientists refer to Pluto and Charon as a double dwarf planet, double planet or binary system. Pluto and Charon are just 12,200 miles (19,640 km) apart, less than the distance by flight between London and Sydney. Charon's orbit around Pluto takes 6.4 Earth-days, and one Pluto rotation — a Pluto-day — also takes 6.4 Earth-days. This is because Charon hovers over the same spot on Pluto's surface, and the same side of Charon always faces Pluto, a phenomenon known as tidal locking. While Pluto has a reddish tint, Charon appears more grayish. In its early days, the moon may have contained a subsurface ocean, though the satellite probably can't support one today. Compared with most of the solar system's planets and moons, the Pluto-Charon system is tipped on its side in relation to the sun. Observations of Charon by New Horizons have revealed the presence of canyons on the moon's surface. The deepest of those canyons plunges downward for 6 miles (9.7 km). A long swatch of cliffs and troughs stretches for 600 miles (970 km) across the middle of the satellite. A section of the moon's surface near one pole is covered in a much darker material than the rest of the planet. Similar to regions of Pluto, much of Charon's surface is free of craters — suggesting the surface is quite young and geologically active. Scientists saw evidence of landslideson its surface, the first time such features have been spotted in the Kuiper Belt. The moon may have also possessed its own version of plate tectonics, which cause geologic change on Earth. In 2005, scientists photographed Pluto with the Hubble Space Telescope in preparation for the New Horizons mission and discovered two other tiny moons of Pluto, now dubbed Nix and Hydra. These satellites are two and three times farther away from Pluto than is Charon. Based on measurements by New Horizons, Nix is estimated to be 26 miles (42 km) long and 22 miles (36 km) wide, while Hydra is estimated at 34 miles (55 km) long and 25 miles (40 km) wide. It is likely that Hydra's surface is coated primarily in water ice. Scientists using Hubble discovered a fourth moon, Kerberos, in 2011. This moon is estimated to be 8 to 21 miles (13 to 34 km) in diameter. On July 11, 2012, a fifth moon, Styx, was discovered (with an estimated width of 6 miles or 10 km), further fueling the debateabout Pluto's status as a planet. The four newly spotted moons may have formed from the collisionthat created Charon. Their orbits have been found to be highly chaotic. Research & explorationNASA's New Horizonsmission is the first probe to study Pluto, its moons and other worlds within the Kuiper Belt up close. It was launched on January 2006, and successfully made its closest approach to Pluto on July 14, 2015. The last of the data was downloaded to Earth in 2016. New Horizons is now on its way to the Kuiper Belt object 2014 MU69, which it will fly by on Jan. 1, 2019. The New Horizons probe carries some of the ashes of Pluto's discoverer, Clyde Tombaugh. The limited knowledge of the Pluto system created unprecedented dangers for the New Horizons probe. Prior to the mission's launch, scientists knew of the existence of only three moons around Pluto. The discovery of Kerberos and Styx during the spacecraft's journey fueled the idea that more satellites could orbit the dwarf planet, unseen from Earth. Collisions with unseen moons, or even small bits of debris, could have seriously damaged the spacecraft. But the New Horizons design team equipped the space probe with tools to protect itduring its journey. Pluto's formation & originsThe leading hypothesis for the formation of Plutoand Charon is that a nascent Pluto was struck with a glancing blow by another Pluto-size object. Most of the combined matter became Pluto, while the rest spun off to become Charon, this idea suggests. [Infographic: Pluto: A Dwarf Planet Oddity] Additional reporting by staff writer Calla Cofield and by Elizabeth Howell and Nola Taylor Redd, Space.com contributors. Have a news tip, correction or comment? Let us know at firstname.lastname@example.org.
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