12.4 Pluto and Charon
3 min read•june 12, 2024
and , the dynamic duo of the outer Solar System, challenge our understanding of planetary bodies. Their unique orbits, complex surfaces, and intriguing relationship offer a glimpse into the diverse worlds beyond Neptune.
' flyby revealed Pluto's varied geology, from icy mountains to nitrogen plains, hinting at ongoing activity. Charon, nearly half Pluto's size, boasts its own fascinating features, making this pair a captivating subject for planetary scientists.
Pluto and Charon
Pluto's orbit vs planetary orbits
Top images from around the web for Pluto's orbit vs planetary orbits
Orbits in the Solar System | Astronomy View original
Is this image relevant?
Overview of Our Planetary System – Astronomy View original
Is this image relevant?
newtonian gravity - Why does Pluto's orbit cross Neptune's orbit? - Physics Stack Exchange View original
Is this image relevant?
Orbits in the Solar System | Astronomy View original
Is this image relevant?
Overview of Our Planetary System – Astronomy View original
Is this image relevant?
1 of 3
Top images from around the web for Pluto's orbit vs planetary orbits
Orbits in the Solar System | Astronomy View original
Is this image relevant?
Overview of Our Planetary System – Astronomy View original
Is this image relevant?
newtonian gravity - Why does Pluto's orbit cross Neptune's orbit? - Physics Stack Exchange View original
Is this image relevant?
Orbits in the Solar System | Astronomy View original
Is this image relevant?
Overview of Our Planetary System – Astronomy View original
Is this image relevant?
1 of 3
- Pluto's orbit around the Sun highly elliptical and inclined compared to the planets (Earth, Mars, Jupiter)
- Orbital period spans 248 Earth years, much longer than planets in the inner Solar System
- Average distance from the Sun 39.5 AU (5.9 billion km), far beyond Neptune's orbit
- Pluto's orbital resonance with Neptune prevents collisions despite crossing orbits
- Pluto orbits the Sun twice for every three orbits of Neptune, maintaining a stable configuration
- This 2:3 resonance ensures Pluto and Neptune never approach each other closely
- Pluto classified as a based on its orbital and physical characteristics
- Orbits the Sun and has enough mass to achieve a round shape due to self-gravity ()
- Has not cleared its orbital neighborhood of other objects ( Objects), unlike the eight planets
- Considered a due to its orbit beyond Neptune
Surface features from New Horizons data
- New Horizons spacecraft revealed varied surface geology during its 2015 flyby
- Mountainous regions possibly composed of water ice, contrasting with the plains
- Vast plains like likely formed by nitrogen ice, with convection patterns
- Dark, heavily cratered regions () indicating ancient, less altered surfaces
- Evidence of geological activity suggests a complex and dynamic world
- Lack of craters in some regions implies recent resurfacing, possibly by (ice volcanoes)
- Convection cells in the nitrogen ice plains, resembling bubbles, indicate ongoing processes
- Atmospheric haze and possible hydrocarbon compounds add to Pluto's complexity
- Thin atmosphere composed mainly of nitrogen, with traces of methane and carbon monoxide
- Haze layers in the atmosphere and possible surface deposits of complex hydrocarbons () formed by photochemistry
Charon's properties and Pluto relationship
- Charon's size is substantial compared to Pluto, making it a unique satellite
- Diameter about half that of Pluto, larger than any other moon relative to its parent body
- Mass 12% of Pluto's mass, giving the system a (center of mass) outside Pluto
- Pluto-Charon system considered a double or binary system due to their similar sizes
- Barycenter lies outside Pluto, causing both bodies to orbit this point in space
- Charon and Pluto tidally locked, each always showing the same face to the other
- Charon's surface features reveal a complex geological history
- Large chasms and fractures () indicate past tectonic activity
- Evidence of past cryovolcanism seen in mountains surrounding depressions ()
- Dark polar region () possibly composed of organic compounds deposited from Pluto's atmosphere
Surface composition and reflectivity
- Pluto's surface is dominated by nitrogen ice, which forms the smooth plains of
- The varying composition of ices on Pluto's surface contributes to its range of values
- Darker regions with lower albedo may contain more complex organic compounds
- Brighter areas with higher albedo are likely composed of fresher, cleaner ices
Key Terms to Review (25)
Albedo: Albedo is the measure of the reflectivity of a surface, specifically the ratio of the amount of light or radiation reflected by a body or surface to the amount of light or radiation incident upon it. It is an important concept in understanding the energy balance and thermal properties of planetary bodies, as well as the behavior of various solar system objects.
Asteroids: Asteroids are small, rocky bodies that orbit the Sun, primarily found in the asteroid belt between Mars and Jupiter. They vary in size and shape, with some being large enough to be considered dwarf planets if they were spherical.
Barycenter: The barycenter is the point around which a system of objects, such as a planetary system or a binary star system, orbits. It is the center of mass of the system, where the combined gravitational forces of all the objects are balanced.
Charon: Charon is the largest moon of the dwarf planet Pluto, discovered in 1978. It is a unique and intriguing celestial body that has fascinated astronomers for decades due to its unusual characteristics and its close relationship with Pluto.
Cryovolcanism: Cryovolcanism refers to the process of volcanic activity on icy planetary bodies, where the magma or other erupted materials are composed primarily of volatile compounds like water, methane, or ammonia rather than the silicate-based magma found on Earth. This type of volcanism is observed on various moons and dwarf planets in the outer solar system.
Cthulhu Macula: Cthulhu Macula is a dark, elliptical feature on the surface of Pluto's largest moon, Charon. It is one of the most prominent and intriguing geological formations observed on this distant celestial body.
Dwarf planet: A dwarf planet is a celestial body that orbits the Sun and has sufficient mass for its self-gravity to assume a nearly round shape, but has not cleared its neighboring region of other objects. It differs from a planet in that it does not dominate its orbit.
Dwarf Planet: A dwarf planet is a celestial body that orbits the Sun, is large enough to be rounded by its own gravity, but has not cleared the area of its orbit of other objects. Dwarf planets are a distinct category of objects in the solar system, separate from both planets and smaller solar system bodies like asteroids or comets.
Hydrostatic equilibrium: Hydrostatic equilibrium is the balance between the inward gravitational force and the outward pressure within a star. This balance maintains the star's spherical shape and prevents it from collapsing or expanding uncontrollably.
Hydrostatic Equilibrium: Hydrostatic equilibrium is a state of balance where the gravitational force acting on a body is exactly balanced by the buoyant force, resulting in a stable, stationary state. This concept is fundamental to understanding the composition and structure of planets, the sources of energy in stars, and the evolution of stellar objects.
Kubrick Mons: Kubrick Mons is a mountain located on the surface of Pluto's moon, Charon. It is a prominent feature in the Pluto-Charon system and is named after the renowned film director Stanley Kubrick, known for his groundbreaking work in science fiction cinema.
Kuiper belt: The Kuiper Belt is a region of the solar system beyond Neptune, populated with icy bodies and dwarf planets. It is the source of many short-period comets that orbit the Sun in less than 200 years.
Kuiper Belt: The Kuiper Belt is a region of the solar system beyond the orbit of Neptune, containing numerous small icy objects, including dwarf planets like Pluto. This belt of objects orbits the Sun and is considered an important feature in understanding the formation and evolution of the solar system.
Lowell: Percival Lowell was an American astronomer who famously campaigned for the existence of a ninth planet, which led to the discovery of Pluto. He also misinterpreted surface features on Mars as canals built by intelligent beings.
Mordor Macula: Mordor Macula is a dark, elongated feature on the surface of Pluto's moon, Charon. It is a prominent geological formation that has captured the attention of astronomers and planetary scientists studying the Pluto-Charon system.
New Horizons: New Horizons is a NASA spacecraft launched in 2006 with the primary mission of studying Pluto and the Kuiper Belt, the region of the solar system beyond the orbit of Neptune. It is the first spacecraft to explore Pluto and the farthest planetary object ever visited by a spacecraft.
Nitrogen Ice: Nitrogen ice is a solid form of nitrogen that can be found on the surfaces of some celestial bodies in the outer solar system, particularly on Pluto and its moon Charon. This ice is composed of frozen nitrogen molecules and plays a significant role in the geology and climate of these distant worlds.
Pluto: Pluto is a dwarf planet located in the outer reaches of the Solar System. It was once considered the ninth planet from the Sun but was reclassified as a dwarf planet in 2006. Pluto's unique characteristics and its place in the Solar System make it an important object of study in various astronomical topics.
Serenity Chasma: Serenity Chasma is a vast canyon system located on the surface of Pluto, the dwarf planet in our solar system. This prominent geological feature is a key characteristic of Pluto's unique landscape and provides valuable insights into the planet's geological history and evolution.
Sputnik Planitia: Sputnik Planitia is a large, nitrogen-ice filled basin located on the surface of Pluto. It is a prominent feature on the dwarf planet and plays a significant role in understanding the geology and climate of the Pluto-Charon system.
Tholins: Tholins are complex organic compounds formed by the irradiation and chemical processing of simple organic molecules, such as methane, in the atmospheres of planets and moons. They play a crucial role in the understanding of the composition and evolution of celestial bodies, particularly Pluto and its moon Charon.
Tidal Locking: Tidal locking is a phenomenon where a celestial body, such as a moon or a planet, rotates at the same rate as it orbits around another body, causing one side of the body to always face the object it orbits. This synchronization of rotation and orbital period is a result of the gravitational forces between the two bodies.
Tombaugh: Clyde Tombaugh was the American astronomer who discovered Pluto in 1930. His discovery expanded our understanding of the solar system's outer regions.
Tombaugh Regio: Tombaugh Regio is a distinctive feature on the surface of Pluto, consisting of two large, bright, icy regions separated by a dark equatorial band. It is named after Clyde Tombaugh, the American astronomer who discovered Pluto in 1930.
Trans-Neptunian Object: A trans-Neptunian object (TNO) is a small celestial body that orbits the Sun at a greater average distance than the planet Neptune. These distant objects provide valuable insights into the formation and evolution of the outer solar system.