Comet - Wikipedia
Comets usually have highly eccentric elliptical orbits, and they have a wide range of orbital periods, ranging from several years to potentially several millions of years. Short-period comets originate in the Kuiper belt or its associated scattered disc, which lie beyond the orbit of Neptune.
Comets - NASA Science
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 ...
Comets: Everything you need to know | Space
2023年7月31日 · They orbit the sun in highly elliptical orbits that can take hundreds of thousands of years to complete. As a comet approaches the sun, it heats up very quickly causing solid ice to turn...
Comet | Definition, Composition, & Facts | Britannica
2024年10月28日 · comet, a small body orbiting the Sun with a substantial fraction of its composition made up of volatile ices. When a comet comes close to the Sun, the ices sublimate (go directly from the solid to the gas phase) and form, along with entrained dust particles, a bright outflowing atmosphere around the comet nucleus known as a coma.
Comet: Definition, Tails, Facts, Orbit, Visibility, Difference
2024年9月12日 · The comet follows a regular orbit of 71 years around the Sun. Comet C/2023 A3 will make its closest approach to Earth on June 2, 2024, at a distance of 144 million miles. The comet reaches its closest point to the Sun, known as perihelion, at 1.18 AU on April 21, 2024.
What Is a Comet? | NASA Space Place – NASA Science for Kids
2024年11月8日 · 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.
Why Comets Are Important - NASA Solar System Exploration
2000年6月7日 · They have highly elliptical orbits that repeatedly bring them very close to the Sun and then swing them deeply into space, often beyond the orbit of Pluto. * Comet structures are diverse and very dynamic, but they all develop a surrounding cloud of diffuse material, called a coma, that usually grows in size and brightness as the comet ...
Comets explained: An essential guide to the snow cones of space
2023年10月16日 · Comets’ orbits can be very long, meaning they may spend most of their time in far-off reaches of the solar system. An object will orbit faster the closer it is to the Sun, as angular momentum...
In Depth | 1P/Halley – NASA Solar System Exploration
Comet Halley moves backward (opposite to Earth's motion) around the Sun in a plane tilted 18 degrees to that of the Earth's orbit. Halley's backward, or retrograde, motion is unusual among short-period comets, as its greatest distance from the Sun (aphelion) is …
Comet - Orbit, Tail, Nucleus | Britannica
2024年10月28日 · Jupiter-family comets typically have orbits that are modestly inclined to the ecliptic (the plane of Earth’s orbit), with inclinations up to about 35°. Halley-type comets can have much higher inclinations, including retrograde orbits that go around the Sun in the opposite direction, though not totally randomized. The long-period comets have ...