Results for “what is a comet” · retrieved September 22, 2026
A comet is a celestial body made of ice, dust, and rock that orbits the Sun and develops a glowing head and long tail when it nears the Sun's heat.
Often described as cosmic snowballs or dirty snowballs, comets are ancient, frozen remnants from the formation of the solar system 4.6 billion years ago. They consist of a solid nucleus made of ice, rock, and dust. When their elliptical orbits bring them close to the Sun, the heat causes the ice to sublimate, releasing gas and dust. This creates a large, fuzzy atmosphere called a coma and often produces two distinct tails: a white dust tail and a bluish ion tail that points away from the Sun. Most comets originate from the Kuiper Belt or the distant Oort Cloud.
Answer details
The Nucleus
The nucleus is the solid, frozen heart of a comet, typically a few kilometers across and composed of water ice, volatile gases, and silicate dust.
The Coma
As a comet approaches the Sun, its ices sublimate, creating a large, fuzzy atmosphere of gas and dust around the nucleus known as the coma.
The Tails
Comets often display two tails: a curved dust tail and a straight, bluish ion tail that always points directly away from the Sun due to solar wind.
Origin and Orbit
Most comets reside in the Kuiper Belt or the Oort Cloud and travel in highly elliptical orbits that bring them into the inner solar system.
Sources 8
About this answerComets
Comets are cosmic snowballs of frozen gases, rock, and dust that orbit the Sun. When frozen, they are the size of a small town. When a comet's orbit brings it close to the Sun, it heats up and spews dust and gases into a giant glowing head larger than most planets. The dust and gases form a tail that stretches away from the Sun for millions of miles. There are likely billions of comets orbiting our Sun in the Kuiper Belt and even more distant Oor
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What Is a Comet? | NASA Space Place – NASA Science for Kids
The Short Answer: Comets are large objects made of dust and ice that orbit the Sun. Best known for their long, streaming tails, these ancient objects are leftovers from the formation of the solar system 4.6 billion years ago....Comets, such as the comet ISON pictured here, are thought to hold material from the time when the Sun and planets were forming. They are like giant, frozen time capsules in our solar system. Credit: NASA/MSFC/Aaron Kingery
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Comet - Nucleus, Tail, Orbit | Britannica
Telescopic observations from Earth and spacecraft missions to comets have revealed much about their nuclei. Cometary nuclei are small solid bodies, typically only a few kilometres in diameter and composed of roughly equal parts of volatile ices, fine silicate dust, and organic materials. The ices are dominated by water ice (about 80 percent of the total ices) but also include carbon monoxide, carbon dioxide, formaldehyde, and methanol. The silica
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Comet Facts
Comets are leftovers from the dawn of our solar system around 4.6 billion years ago, and consist mostly of ice coated with dark organic material. They have been referred to as "dirty snowballs." They may yield important clues about the formation of our solar system. Comets may have brought water and organic compounds, the building blocks of life, to the early Earth and other parts of the solar system. Comets Home about Comet Facts...We now know t
November 15, 2017
ESA - Comets: an overview
With a name derived from the Greek komētēs, meaning a 'long-haired' star, comets are ancient celestial icebergs of the Solar System. Each comet is roughly 4600 million years old and formed at the same time as the Sun, Earth and the other planets....The defining characteristic of a comet is its tail – the long 'hair' to which the Greeks referred. Tails come in two main types, ion (or plasma) and dust. When sunlight evaporates the ice on the comet’
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Comet
Main PageWelcome to Wikipediathe free encyclopedia that anyone can edit.- 256,267 active editors- 7,235,150 articles in EnglishFrom today's featured articleHeard IslandHeard Island and McDonald Islands is an external territory of Australia in the southern Indian Ocean. It is a group of sub-Antarctic volcanic islands that lie on the Kerguelen Plateau. It is about 4,000 km (2,500 mi) south-west of the Australian mainland and 1,700 km (1,100 mi
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What is a comet? | BBC Sky at Night Magazine
Simply put, a comet is a large body of ice and dust orbiting the Sun, sometimes seen as a bright object in the sky with a long tail streaming behind it....The heart of a comet is its nucleus, a core of ice laced with rock and dust, a few kilometres wide....Comets travel in huge elliptical orbits, briefly visiting the inner Solar System at one end before travelling billions of kilometres to the outer regions....For most of a comet's orbit, the nuc
August 26, 2025
ESA - What types of comets are there?
In essence, all comets are clumps of ice and dust. When they fly close to the Sun, they heat up and spew out gases and dust, enveloping the solid nucleus in a large hazy cloud called a coma and often producing one or more lengthy tails. We classify different types of comets based on their flight path through space....Comets are icy remnants from the birth of the outer planets in our Solar System. They lost the gravitational tug-of-war to the larg
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