13.4 The Origin and Fate of Comets and Related Objects
3 min read•june 12, 2024
Comets, , and are fascinating icy bodies that roam our solar system. These remnants from the early days of planetary formation offer crucial insights into the composition and evolution of our cosmic neighborhood.
From the to the inner solar system, these objects display diverse behaviors and characteristics. Their interactions with planets, the Sun, and each other shape their orbits and fates, sometimes leading to spectacular displays or even collisions that impact planetary surfaces.
Comets and Related Objects in the Solar System
Characteristics of centaur objects
Icy objects orbiting between Jupiter and Neptune
Unstable orbits influenced by gravitational pull of gas giants
Likely originated from the or
Range in diameter from tens to hundreds of kilometers
Made up of rock, dust, and various ices (water, methane, ammonia)
Some display cometary activity ( and tail) near (closest approach to the Sun)
Provide insights into composition and evolution of outer solar system
Act as transitional objects between objects and
Studying centaurs helps understand dynamic processes in solar system
Oort cloud's composition and significance
Hypothesized by in 1950 to explain origin of
Spherical cloud surrounding solar system up to 100,000 AU away
Contains billions of icy objects left over from solar system formation
Primarily composed of icy (water, methane, ammonia, dust)
Objects range in size from small particles to kilometer-sized bodies
Gravitational perturbations from passing stars or galactic tides can disrupt objects
Disrupted objects may enter inner solar system as long-period comets (orbital periods > 200 years)
cloud is the source of most observed long-period comets
Studying Oort cloud helps understand the origin and evolution of comets in solar system
Include Kuiper belt objects (KBOs), scattered disk objects, detached objects
Kuiper belt objects orbit within flat, donut-shaped region 30-50 AU from Sun
Composed of icy bodies similar to comets
Examples: , , ,
Similarities between TNOs and KBOs
Remnants from early solar system formation
Primarily made of ices and rock
Orbits influenced by Neptune's gravitational perturbations
Differences between TNOs and KBOs
Some TNOs (scattered disk and detached objects) have more eccentric and inclined orbits than KBOs
Scattered disk objects likely ejected from Kuiper belt by interactions with Neptune
Detached objects have orbits not significantly influenced by Neptune
Comets in inner solar system
Gravitational interactions with planets can alter comet orbits
Ejection from solar system
Capture into shorter-period orbit (Jupiter-family comets)
Comets can break apart due to or thermal stress
Fragments may continue orbiting or collide with planets or moons
Collision with Sun or planet
Comets passing too close to Sun may disintegrate or collide
Impact events can occur on planets or moons, affecting surfaces and atmospheres
Studying comet orbits and interactions refines models of solar system formation and evolution
Cometary impacts provide insight into role of collisions in shaping planetary surfaces and atmospheres
Composition of comets offers clues about chemical makeup of early solar system and distribution of materials during planetary formation
Comet Structure and Behavior
: The solid, icy core of a comet, typically a few kilometers in diameter
Coma: Atmosphere of gas and dust surrounding the , formed by as the comet approaches the Sun
Tail: Streams of gas and dust pushed away from the comet by solar radiation and solar wind
: Measure of a comet's reflectivity, typically very low due to dark, carbon-rich surface materials
: Gravitational relationship between a comet and a planet, influencing the comet's orbit and potentially leading to capture or ejection from the solar system
Key Terms to Review (33)
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.
Centaur Objects: Centaur objects are a class of minor planets in the Solar System that have orbits between those of the giant planets, typically crossing or overlapping the orbits of one or more of the gas giants. They are considered to be transitional objects between the icy bodies of the outer Solar System and the rocky bodies of the inner Solar System.
Centaurs: Centaurs are small celestial bodies that have characteristics of both asteroids and comets. They typically orbit the Sun between Jupiter and Neptune, displaying unstable orbits due to gravitational interactions with these giant planets.
Chiron: Chiron is a celestial object classified as both a comet and an asteroid, known as a centaur. It orbits between Saturn and Uranus and was discovered in 1977 by Charles Kowal.
Coma: The coma is the bright, diffuse, cloud-like region surrounding the nucleus of a comet, formed by the evaporation of ice and other volatile materials as the comet approaches the Sun. It is a key feature that distinguishes comets from other celestial objects, giving them their distinctive 'long-haired' appearance.
Coma cluster: The Coma Cluster is a large cluster of galaxies located in the constellation Coma Berenices. It is one of the richest and most densely populated galaxy clusters known, containing thousands of galaxies.
Comet Halley: Comet Halley, also known as Halley's Comet, is a periodic comet visible from Earth every 75–76 years. It is one of the most well-known and bright comets, with its last appearance in 1986 and next expected in 2061.
Comet LINEAR: Comet LINEAR is a comet discovered by the Lincoln Near-Earth Asteroid Research project in 2000. It has a highly elliptical orbit that brings it close to the Sun and then out to the far reaches of the Solar System.
Comet Shoemaker-Levy 9: Comet Shoemaker-Levy 9 was a comet that famously collided with Jupiter in July 1994. It provided a unique opportunity to study the impact of a comet on a planetary body and its consequences.
Eris: Eris is a dwarf planet in the outer Solar System, and the most massive and second-largest known dwarf planet in the Solar System after Pluto. It is a significant object in the context of understanding the formation and evolution of our planetary system.
Haumea: Haumea is a dwarf planet located in the Kuiper Belt, a region of the Solar System beyond the orbit of Neptune. It is one of the largest known objects in the Kuiper Belt and is characterized by its unique elongated shape and rapid rotation.
Haumea's significance is primarily related to its classification as a dwarf planet, as well as its potential insights into the formation and evolution of the Solar System's outer regions, including the origin and fate of comets and related objects.
Jan Oort: Jan Oort was a Dutch astronomer who made significant contributions to our understanding of the origin and distribution of comets in the solar system. His work laid the foundation for the concept of the Oort Cloud, a vast spherical shell of icy objects surrounding the Sun that serves as the source of long-period comets.
Jupiter-family comets: Jupiter-family comets are a class of short-period comets that have orbits primarily influenced by the gravitational pull of Jupiter. These comets have orbital periods of less than 20 years and typically originate from the Kuiper Belt or the scattered disc, regions beyond the orbit of Neptune.
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.
Levy: A levy is an astronomical term for a comet or asteroid that has been discovered and officially named. These objects often carry the surname of their discoverer, such as "Comet Levy."
Long-Period Comets: Long-period comets are a class of comets with orbital periods greater than 200 years, often taking thousands of years to complete a single orbit around the Sun. These comets originate from the Oort Cloud, a distant reservoir of icy objects at the edge of the Solar System, and are believed to have been perturbed from their stable orbits by the gravitational influence of passing stars or galactic tides.
Makemake: Makemake is a dwarf planet located in the Kuiper Belt, a region of the outer Solar System beyond the orbit of Neptune. It is the second-brightest object in the Kuiper Belt, after Pluto, and was discovered in 2005. Makemake is a member of the Kuiper Belt Objects (KBOs), which are a class of distant, icy bodies that orbit the Sun beyond the orbit of Neptune.
Nucleus: The nucleus is the central core of an atom, containing protons and neutrons. It is positively charged and holds most of the atom's mass.
Nucleus: The nucleus is the central and most important part of an atom, containing protons and neutrons. It is the core of an atom that holds the majority of its mass and positive charge, and it is the defining feature of an atom's identity and properties.
Oort: The Oort Cloud is a hypothetical spherical shell of icy objects believed to surround the Sun at distances ranging from 2,000 to 100,000 astronomical units (AU). It is thought to be the source of long-period comets entering the inner solar system.
Oort cloud: The Oort Cloud is a hypothetical, distant region of the Solar System that is believed to surround the Sun with a vast shell of icy bodies. It is thought to be the source of most long-period comets that enter the inner Solar System.
Oort Cloud: The Oort Cloud is a hypothetical spherical cloud of icy objects that is believed to surround the Solar System at a vast distance. It is considered the source of long-period comets that enter the inner Solar System. The Oort Cloud plays a crucial role in our understanding of the formation and evolution of the Solar System, as well as the origin and fate of comets and related objects.
Orbital Resonance: Orbital resonance is a phenomenon that occurs when two or more celestial bodies exert a regular, periodic gravitational influence on each other, causing their orbits to become synchronized. This concept is crucial in understanding the dynamics and evolution of various systems within the solar system.
Perihelion: Perihelion is the point in the orbit of a planet, asteroid, or comet where it is closest to the Sun. At this point, the celestial body travels at its maximum orbital velocity due to the gravitational pull of the Sun.
Perihelion: Perihelion is the point in a planet's or comet's orbit when it is closest to the Sun. This is a crucial concept in understanding the motions and behaviors of objects within our solar system.
Planetesimals: Planetesimals are small celestial objects that formed from dust and gas in the early solar system. They serve as the building blocks of planets through a process called accretion.
Planetesimals: Planetesimals are the small, rocky or icy bodies that formed the building blocks of the planets in the early stages of the Solar System's development. These objects, ranging from just a few kilometers to hundreds of kilometers in size, gradually accumulated through the process of accretion to eventually create the larger planetary bodies we see today.
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.
Scattered Disk: The scattered disk is a region of the outer Solar System beyond the orbit of Neptune that contains a large number of small icy objects, known as scattered-disk objects (SDOs). These objects have orbits that are typically more distant and inclined to the plane of the Solar System compared to the objects in the Kuiper Belt.
Sublimation: Sublimation is the process by which a solid substance transitions directly into a gaseous state, bypassing the liquid phase. This phenomenon is particularly relevant in the context of water and ice in planetary science, as well as the formation and behavior of comets and other icy objects in the solar system.
Tidal Forces: Tidal forces are the differential gravitational forces exerted by one body on different parts of another body. These forces arise due to the non-uniform distribution of gravitational acceleration across an object, leading to distortions and deformations in the object's shape.
Trans-Neptunian Objects: Trans-Neptunian Objects (TNOs) are a class of celestial bodies that orbit the Sun at distances greater than the orbit of Neptune. These distant objects provide valuable insights into the formation and evolution of our solar system, particularly the outer regions beyond the orbit of the major planets.