Pluto: Definition, Distance, Size, Discovery, Facts, Color

Pluto is a dwarf planet situated in the Kuiper Belt, a distant region of icy bodies beyond Neptune’s orbit. Pluto is distinguished by its small size, irregular orbit, and classification as a dwarf planet following the 2006 redefinition by the International Astronomical Union. Pluto has reddish-brown surface, composed of frozen gases, and its five known moons, with Charon being the largest. Pluto’s discovery in 1930 by Clyde Tombaugh marked a significant advancement in astronomy and our understanding of the outer solar system. Learn about Pluto’s unique characteristics, its demotion from planetary status, and its role in exploring the Kuiper Belt’s composition and history.

Pluto’s average distance from Earth is 5.05 billion kilometers (3.1 billion miles). Pluto has a diameter of 2,376.6 km (1,473 miles), making it the largest known trans-Neptunian object by volume. Pluto is smaller than Earth’s moon, with a diameter of 2,377 km (1,477 miles) and a radius of 1,188.3 km (737 miles).

Clyde Tombaugh discovered Pluto on February 18, 1930, while working at the Lowell Observatory in Arizona. Astronomers designated Pluto a planet until its reclassification as a dwarf planet in 2006. The discovery marked a milestone in astronomical history and expanded our understanding of the outer solar system.

Pluto features a heart-shaped area on its surface known as Tombaugh Regio. The dwarf planet has five known moons, with Charon being the largest at half Pluto’s diameter. Pluto’s orbit is eccentric, ranging from 30 to 49 astronomical units from the Sun, and it completes one orbit every 248 Earth years. The surface of Pluto includes mountains made of water ice, valleys, plains, and craters.

Pluto’s color exhibits tones of blues, yellows, and reds. Tholins contribute to Pluto’s reddish hues and color profile. The dwarf planet appears to human eyes with off-white to orange hues. Enhanced images from the New Horizons spacecraft show pale blue to deep red tones across Pluto’s surface. The “heart” region, Sputnik Planitia, appears bright white in images taken by New Horizons.

What is the dwarf planet Pluto?

Pluto is a dwarf planet located in the Kuiper Belt, an icy region beyond Neptune’s orbit. Pluto was reclassified as a dwarf planet in 2006 by the International Astronomical Union. Pluto orbits the Sun but has not cleared its orbital neighborhood.

Pluto has a diameter of about 1,400 miles (2,250 kilometers). Pluto’s size is half the width of the United States. Pluto’s surface appears reddish-brown due to its composition of methane and nitrogen ices. Pluto has five known moons: Charon, Nix, Hydra, Styx, and Kerberos. Charon is the largest moon, measuring about half the size of Pluto itself.

Pluto orbits the Sun in the Kuiper Belt, a region beyond Neptune’s orbit. Pluto’s distance from the Sun is 39.5 astronomical units (AU), 5.91 billion kilometers or 3.67 billion miles. Pluto’s orbit is eccentric and inclined, ranging from 30 to 49 AU from the Sun.

The International Astronomical Union (IAU) defines a dwarf planet as a celestial body that orbits the Sun, has sufficient mass to assume hydrostatic equilibrium, and has not cleared its orbital neighborhood. Pluto meets the first two criteria but fails the third. Pluto is classified as a plutoid, a subset of dwarf planets orbiting beyond Neptune. Dwarf planets differ from planets by not being gravitationally dominant in their orbits.

Clyde Tombaugh, an astronomer, discovered Pluto in 1930. Pluto was initially categorized as the ninth planet in the solar system. The IAU reclassified Pluto as a dwarf planet in 2006 as part of an effort to define and categorize celestial bodies in the solar system.

When did Pluto stop being a planet?

Pluto stopped being a planet in August 2006. The International Astronomical Union downgraded Pluto’s status from planet to dwarf planet during its General Assembly. This decision aligned with the precise definition of a planet.

The reclassification of Pluto occurred 76 years after its discovery in 1930. Clyde Tombaugh spotted Pluto, and it was named the ninth planet in our solar system for over seven decades. The International Astronomical Union (IAU) made the decision to reclassify Pluto during their 26th General Assembly in August 2006. Pluto met the criteria to be classified as a planet, but failed to clear its orbit of other objects in the Kuiper Belt.The year 2024 marks 18 years since Pluto’s status as a planet was called into question. Pluto is classified as a dwarf planet and as a plutoid, a subcategory of trans-Neptunian objects within the Kuiper Belt. The debate over Pluto’s status continues among some astronomers and planetary scientists, despite the IAU’s definition since 2006.

Why was Pluto demoted?

Pluto was demoted because it failed to meet the International Astronomical Union’s criteria for planet classification. Pluto doesn’t clear its orbital neighborhood, sharing its region with Kuiper Belt objects. In 2006, the IAU reclassified Pluto as a dwarf planet.

Pluto’s size and composition were influencing factors in its demotion. Pluto has a diameter of 2,253 kilometers (1,400 miles), making it smaller than Earth’s moon. The discovery of Eris in 2005 challenged Pluto’s planetary status. Eris is 27% more massive than Pluto and larger in size.

Pluto’s orbit and neighborhood were critical factors in its reclassification. Pluto’s orbit overlaps with Neptune’s, and it resides within the Kuiper Belt. The Kuiper Belt is a donut-shaped region beyond Neptune containing millions of rocky and icy bodies. Kuiper Belt objects are similar in size to Pluto, including Eris, Haumea, and Makemake.

The International Astronomical Union (IAU) revised the planet definition in 2006. The IAU established three criteria for planet classification: orbiting the Sun, having sufficient mass for a spherical shape, and clearing its orbital neighborhood. The IAU introduced the “dwarf planet” category for bodies meeting the first two criteria but failing the third.

Pluto failed to meet the IAU’s third criterion for planet status. Pluto orbits the Sun and has a round shape due to its gravity. Pluto has not cleared its orbital neighborhood and is not gravitationally dominant in its region. The IAU reclassified Pluto as a dwarf planet based on these criteria.

The reclassification of Pluto led to a reassessment of celestial body classifications. The IAU’s decision provided a framework for distinguishing planets from dwarf planets. This reclassification reflected an enhanced understanding of solar system structure. The Kuiper Belt was recognized as a region beyond Neptune’s orbit, containing a population of celestial bodies and dwarf planets.

How far is Pluto from Earth?

Pluto is at an average distance of 5.05 billion kilometers or 3.1 billion miles from Earth. The distance varies due to the elliptical orbits of both planets, ranging from 4.28 billion kilometers at the closest to 7.5 billion kilometers at the most distant point.

Pluto reaches its closest approach to Earth at 2.66 billion miles (4.28 billion km). The dwarf planet increases its separation to 4.67 billion miles (7.5 billion km) at its most distant point. Distances between Earth and Pluto vary depending on the source. One estimate puts the average at 3.7 billion miles (5.9 billion km), while another calculates it at 5.05 billion km (3.1 billion miles).

Measurements show Pluto’s distance from Earth at 5,402,390,273 km (36.112748 au). The minimum centre-to-centre distance between Earth and Pluto in 2025 is 5,093,180,949 km (3,164,000,000 miles). Largest separation occurs when Earth and Pluto are farthest apart, reaching a distance of 50.3 au. Pluto’s elliptical orbit contributes to these variations in distance from Earth.

How far is Pluto from the Sun?

Pluto’s distance from the Sun varies due to its orbit. The average distance is 39.5 AU or 3.67 billion miles (5.906 billion kilometers). At its closest, Pluto is 2.76 billion miles from the Sun and at the farthest it is 4.58 billion miles.

Pluto follows an elliptical orbit around the Sun. Its distance from the Sun varies, ranging from 30 AU at its closest approach to 50 AU at its farthest point. Pluto’s average distance from the Sun measures 34.05 AU. Astronomers consider Pluto one of the most distant objects in our solar system. Light from the Sun requires 5.5 hours to reach Pluto at its average orbital distance.

Pluto holds the title of the dwarf planet with the greatest average distance from the Sun. Other dwarf planets like Eris can reach distances farther than Pluto at their most distant points.

Is Pluto drifting away?

Pluto is drifting away from the Sun. Pluto’s movement away from the Sun began after its closest approach between 1979 and 1999. As Pluto moves farther from the Sun, its atmosphere condenses and freezes, falling onto the surface.

Neptune’s gravitational interaction plays a part in Pluto’s movement through a 3:2 orbital resonance with Pluto. This resonance acts as a stabilizing mechanism, preventing Pluto’s orbit from intersecting Neptune’s. Charon, Pluto’s largest moon, exerts a substantial gravitational influence, forming a binary system with Pluto. The solar system’s gravitational structure, dominated by the Sun’s mass, affects Pluto’s orbital dynamics.
Pluto resides in the Kuiper Belt, a region of icy bodies beyond Neptune’s orbit. The Kuiper Belt is characterized by intricate gravitational interactions. Pluto’s orbit is eccentric, ranging from 30 to 49 astronomical units (AU) from the Sun. This eccentricity results in variations in Pluto’s distance from the Sun over its 248-year orbital period.

Measurements of Pluto’s drift rate show no considerable steady movement away from the Sun. Pluto’s orbital parameters undergo variations over time. The dwarf planet’s semi-major axis varies between 39.3 and 39.6 AU over a period of 19,951 years. Pluto’s orbital period fluctuates between 246 and 249 years due to these gravitational influences. The 3:2 resonance with Neptune ensures stability in Pluto’s orbit, preventing drift or escape from the solar system.

Is Pluto farther than Neptune?

Pluto is farther than Neptune for most of its orbit. Pluto slips inside Neptune’s orbit every 248 years, remaining closer to the Sun for 20 years. This last occurred from 1979 to 1999.

Pluto’s distance from the Sun is 39.5 astronomical units (AU). Neptune’s average distance from the Sun is 30.06 AU. Pluto’s orbit around the Sun is elliptical. Pluto’s distance from the Sun varies, ranging from 29.7 AU at its closest point (perihelion) to 49.3 AU at its farthest point (aphelion).

The Sun holds a central position in our solar system. Pluto is located in the Kuiper Belt, which extends from 30 to 55 AU from the Sun. Pluto’s orbit extends farther from the Sun than Neptune’s at its aphelion. Pluto is part of the Kuiper Belt beyond Neptune’s orbit. Our solar system’s extent reaches beyond Pluto, encompassing the Kuiper Belt and the distant Oort Cloud.

How big is the planet Pluto?

The planet Pluto has a diameter of 2,376.6 km (1,473 miles). Pluto’s size makes it the largest known trans-Neptunian object by volume, though smaller than Earth’s moon. Pluto’s dimensions classify it as a dwarf planet.

Pluto’s size has been a subject of debate since its discovery in 1930. NASA’s New Horizons mission provided accurate measurements in 2015. The mission confirmed Pluto’s diameter as 2,376.6 km (1,473 miles), with an equatorial diameter of 2,377 km (1,477 miles). Pluto has a radius of 1,188.3 km (737 miles). Pluto’s size in comparison to Earth is 0.1868, making it five times smaller than our planet. The dwarf planet’s mass is estimated at 1.31 x 10^22 kg (2.89 x 10^22 lbs), one-sixth the mass of Earth’s moon. Pluto’s volume measures about 1.5 billion cubic miles (6.97 × 10^9 cubic kilometers).

How old is Pluto?

Pluto is 4.5 billion years old. This dwarf planet formed early in the solar system’s history, alongside other celestial bodies. Pluto’s age matches that of the Kuiper Belt, an area of icy objects beyond Neptune’s orbit.

Pluto’s age is estimated to be 4.5 billion years. The dwarf planet formed during the same period as the rest of the solar system, which is believed to have originated 4.35 to 4.6 billion years ago. Pluto has existed in the Kuiper Belt since the early days of our neighborhood. The reclassification of Pluto as a dwarf planet in 2006 does not affect its origins.

Human awareness of Pluto spans a fraction of its existence. Humans have known about Pluto for 93 years since its discovery by Clyde Tombaugh in 1930. Pluto has completed less than half an orbit around the Sun since its discovery, with one Pluto year lasting 248 Earth years.

How was Pluto formed?

Pluto formed through the coalescence of particles in the outer solar system. An impact between two objects led to the formation of Pluto and Charon as a binary system. The process involved accretion of particles from the disk around the Sun, resulting in a gravitationally bound pair.

Pluto formed within the protoplanetary disk of the early solar system. Dust aggregation and gas dynamics in the disk created the building blocks for planetesimals. The Solar Nebula had a temperature gradient that influenced the composition of materials available for Pluto’s formation. Planetesimals in the Kuiper Belt region underwent collisional growth and aggregation processes. Pluto accreted material over time, growing in size and undergoing differentiation. The differentiation process resulted in Pluto’s rocky core and icy mantle structure.

Pluto experienced a collision early in its history. The Giant Impact Hypothesis explains the formation of Charon through an impact event. The collision ejected debris that coalesced to form Pluto’s smaller moons. Pluto and Charon became gravitationally bound, creating a binary system. The impact event occurred, aligning with a “hot start” model of Pluto’s formation. Pluto’s orbit resulted from gravitational interactions with Neptune during its dynamical evolution.

Trans-Neptunian Objects in the Kuiper Belt share a composition with Pluto. These objects underwent accretion histories and collisional evolution processes. The dynamical evolution of Trans-Neptunian Objects influenced the current structure of the Kuiper Belt. Pluto’s formation and evolution connect to the evolution of the outer solar system.

Who discovered Pluto?

Clyde Tombaugh discovered Pluto on February 18, 1930. Tombaugh, an astronomer, worked at the Lowell Observatory in Arizona. Astronomers initially named Pluto the ninth planet, but it was reclassified as a dwarf planet in 2006.

What is Pluto named after?

Pluto is named after the Roman god of the underworld. The planet’s nature reflected the god’s association with death and wealth found in the earth, making the name appropriate.

Venetia Burney, an 11-year-old schoolgirl from Oxford, England, suggested the name Pluto for the discovered celestial body in 1930. Burney proposed the name to her grandfather, who forwarded it to astronomer Herbert Hall Turner. Turner telegraphed the suggestion to the Lowell Observatory, where astronomers voted to adopt the name Pluto on May 1, 1930.

Clyde Tombaugh discovered Pluto on February 18, 1930, at the Lowell Observatory. Tombaugh conducted a search for a ninth planet, using a blink comparator to detect moving objects in photographic plates. The name Pluto honored Percival Lowell, the founder of Lowell Observatory, as his initials PL are the first two letters of the planet’s name.

Pluto was classified as the ninth planet in the solar system. The International Astronomical Union reclassified Pluto as a dwarf planet in 2006. Pluto retained its name referencing the god of the underworld after reclassification. Features on Pluto’s surface have underworld-themed names, following the naming convention established in 1930.

What are some interesting facts about Pluto?

Facts about Pluto include its reclassification as a dwarf planet in 2006, its heart-shaped region, and its five moons. Pluto’s diameter is less than one-fifth of Earth’s. Its surface features mountains, craters, and ices that form an atmosphere when closer to the Sun.

Some interesting facts about Pluto are listed below.

• Pluto’s reclassification: In 2006, Pluto was reclassified as a dwarf planet by the International Astronomical Union.
• Heart-shaped region: Known as Tombaugh Regio, Pluto features a distinctive heart-shaped area on its surface.
• Pluto’s moons: Pluto has five known moons, namely Charon, Nix, Hydra, Kerberos, and Styx, with Charon being the largest and half Pluto’s diameter.
• Diameter of Pluto: Pluto’s diameter is approximately 2,370 kilometers (1,474 miles), two-thirds the size of Earth’s Moon.
• Pluto’s orbit: The eccentric orbit of Pluto ranges from 30 to 49 astronomical units from the Sun, completing an orbit every 248 Earth years.
• Surface features: Pluto’s surface includes mountains made of water ice, valleys, plains, and craters.
• Pluto’s atmosphere: Pluto’s atmosphere is thin, composed mainly of nitrogen, with traces of methane and carbon monoxide.
• Surface temperature: Pluto is one of the coldest places in our solar system, with temperatures ranging from -233 to -223 degrees Celsius.
• Discovery: Clyde Tombaugh discovered Pluto in 1930.
• New Horizons mission: NASA’s New Horizons spacecraft’s flyby in 2015 provided detailed images of Pluto’s surface and atmosphere.
• Kuiper Belt: Pluto is the largest known object in the Kuiper Belt, a region beyond Neptune filled with icy rocks.
• Orbital resonance: Pluto and Neptune share a 2:3 orbital resonance, with Neptune influencing Pluto’s orbit; Pluto completes two orbits around the Sun for every three orbits Neptune makes.
• Tidal locking with Charon: Pluto and its moon Charon are tidally locked, with Charon orbiting Pluto every 6.4 Earth days.

Pluto’s surface features a terrain of mountains, valleys, plains, and craters. Water ice composes Pluto’s tallest mountains, reaching heights of 2 to 3 kilometers (1.24 to 1.86 miles). Frozen nitrogen gas forms plains on Pluto’s surface, showing signs of convection and tectonic activity. Pluto’s atmosphere is thin and composed of nitrogen, with traces of methane and carbon monoxide. Pluto’s surface temperatures range from -233 (-387.4) to -223 (-369.4) Celsius, making it one of the coldest places in our solar system.

What color is Pluto?

Pluto’s surface exhibits blue, yellow, and red tones. Tholins, complex organic compounds, contribute to Pluto’s reddish hues and color profile.

Pluto’s color appears grayish to human eyes. New Horizons spacecraft captured images revealing Pluto’s appearance as off-white to subtle orange hues. Pluto is brown to reddish-brown in color. The dwarf planet’s surface ranges from black to orange in regions. Enhanced images from New Horizons show pale blue to deep red tones across Pluto’s surface. Areas of white, tan, and brownish-red are on Pluto’s terrain. Representations depict Pluto as blue, contrasting with its actual appearance. The “heart” region on Pluto, known as Sputnik Planitia, appears bright white in images taken by New Horizons. Pluto’s moon Charon exhibits a grey coloration compared to Pluto’s reddish hues.

Does Pluto have rings?

Pluto does not have rings. Searches by ground-based telescopes, the Hubble Space Telescope, and the New Horizons spacecraft have confirmed the absence of rings around Pluto. Research indicates Pluto’s outer atmosphere lacks the conditions necessary for ring formation.

The New Horizons spacecraft’s 2015 flyby provided evidence of Pluto’s lack of rings. Resolution imaging and analysis of the Pluto system revealed no ring structures. Pluto’s largest moon, Charon, plays a part in preventing ring formation. Charon’s strong gravitational influence disrupts potential ring-forming material. The moons Hydra, Nix, Styx, and Kerberos contribute to the dynamic stability of the Pluto system. These moons’ orbital parameters create surroundings unsuitable for ring formation.

Pluto’s atmosphere lacks the density required to support ring particles. Nearby Kuiper Belt objects do not provide suitable material for ring formation. Pluto’s environment contains insufficient debris or dust to accumulate into rings.

How many moons does Pluto have?

Pluto has five moons. Charon is half Pluto’s size. Nix, Hydra, Kerberos, and Styx are smaller. Charon was discovered in 1978, while the others were found between 2005 and 2012.

What is the gravity on Pluto?

The gravity on Pluto is 0.063 times Earth’s gravity. Pluto’s surface gravity measures 0.62 meters per second squared (2.03 feet per second squared). A 100-kilogram (220.46 pounds) object on Earth weighs 8 kilograms (17.64 pounds) on Pluto’s surface. Pluto’s low gravity affects its setting and atmosphere.

Pluto’s surface gravity measures 0.62 m/s² (2.03 ft/s²). The equatorial surface gravity of Pluto equals 0.620 m/s² (2.03 ft/s²) or 0.0632 g (0.0632 g) in Earth gravity units. The Pluto fact sheet lists a value of 0.29 m/s² (0.95 ft/s²), while a pendulum clock problem uses 0.610 m/s² (2.00 ft/s²). Pluto’s gravitational pull measures 6-8% of Earth’s gravity. Pluto’s surface gravity equals 1/12 of Earth’s gravity. Pluto’s small size and mass result in its weak surface gravity. Objects fall slowly on Pluto compared to Earth. A person weighing 100 pounds (45.36 kg) on Earth weighs 8 pounds (3.63 kg) on Pluto.

What is the temperature on Pluto?

The temperature on Pluto is cold, averaging 44 Kelvin (-229°C or -380°F). Pluto’s temperature ranges from -387°F (-233°C) to -369°F (-223°C), depending on its distance from the Sun. Surface ices sublimate when Pluto is closest to the Sun, forming a thin atmosphere.

Pluto’s average temperature is -232°C (-387°F). The planet’s surface temperature ranges from -233°C (-387°F) to -223°C (-369°F). Estimated surface temperature ranges extend from -238°C (-396°F) to -228°C (-378°F). Pluto’s surface temperature varies between -230°C ( -382°F) to -210°C ( -346°F) (40K to 60K). Studies indicate a surface temperature range of 30K to 44K. The surface temperature of Pluto is -220°C (-364°F). Pluto’s upper atmosphere temperature is 65-68K. Pluto orbits the Sun at an average distance of 3.6 billion miles, causing its low temperatures. Pluto ranges in temperature due to its orbit and unique axial characteristics. Pluto varies in temperature throughout its 248-year orbit, experiencing extreme seasonal changes.

Does Pluto have a surface?

Pluto has a surface with diversity. New Horizons mission provided data and images revealing ice plains, mountains, and evidence of cryovolcanic activity. Pluto’s surface features include the heart-shaped Tombaugh Regio and ice mountains reaching heights of 6-7 kilometers (3.7-4.3 miles).

Nitrogen ice makes up over 98% of Pluto’s surface, with traces of methane and carbon monoxide. The distribution of these ices varies across Pluto’s surface, with methane abundant on the face oriented toward Charon.

Ice plains like Sputnik Planitia on Pluto’s surface span 1,000 km (621 miles) and are filled with frozen nitrogen and carbon monoxide. Mountains made of water ice reach heights up to 11,000 feet (3,500 meters), similar to Earth’s Rocky Mountains. Craters are unevenly distributed, with some areas heavily cratered and others, like Sputnik Planitia, craterless.

Pluto’s surface geology is active and dynamic. Cryovolcanic structures like Wright Mons indicate ongoing geological processes. Glacial flows of frozen nitrogen, tectonic fractures, and convective overturn in ice plains contribute to Pluto’s evolving terrain.

The New Horizons mission provided insights into Pluto’s surface. High-resolution imaging revealed textures, including polygonal convection cells in Sputnik Planitia and fields of transverse dunes. Data collection confirmed the presence of water ice bedrock assisting Pluto’s mountains and identified intricate organic molecules in the crust.

Pluto’s diameter of 1,473 miles (2,370 km) and mass of 2.88 x 10^21 pounds (1.305 x 10^22 kilograms) influence its surface features. Pluto’s eccentric orbit, averaging 39.5 astronomical units from the Sun, contributes to extreme seasonal variations affecting its surface conditions.

What is Pluto’s atmosphere made of?

Pluto’s atmosphere is made of a thin envelope consisting of nitrogen (98%), with traces of methane (0.25%) and carbon monoxide (0.0515%). Surface ices vaporize to form atmospheric gases. Energy radiation creates compounds that precipitate onto Pluto’s surface.

Nitrogen dominates Pluto’s atmosphere, comprising 98% of its composition. Nitrogen’s volatility influences atmospheric dynamics on Pluto. The abundance of nitrogen in Pluto’s atmosphere stems from its vapor pressure, which reaches 10 Pa at 40 K and increases to 10,000 Pa at 60 K.

Methane plays a vital part in Pluto’s atmosphere despite its trace abundance of 0.25%. Methane’s absorption of sunlight creates a greenhouse effect, heating the atmosphere to 110 K at altitudes. Methane’s photochemistry produces hydrocarbons like ethane, ethylene, and acetylene, which precipitate onto Pluto’s surface and contribute to tholin formation, causing Pluto’s brown color.

Carbon monoxide constitutes 0.0515% of Pluto’s atmosphere. Carbon monoxide’s radiative cooling properties balance atmospheric temperature on Pluto. The interactions between methane and carbon monoxide regulate Pluto’s atmospheric temperature, essential during its seasons lasting decades.