Asteroid | Definition, Size, & Facts | Britannica
3 天之前 · Asteroid, any of a host of small bodies, about 1,000 km (600 miles) or less in diameter, that orbit the Sun primarily between the orbits of Mars and Jupiter in a nearly flat ring called the asteroid belt. Hundreds of thousands of asteroids are known.
Study Finds Earth’s Small Asteroid Visitor Likely Chunk of Moon …
2 天之前 · Asteroid Lunar Studies. The discovery of 2024 PT5 doubles the number of known asteroids thought to originate from the Moon. Asteroid 469219 Kamo’oalewa was found in 2016 with an Earth-like orbit around the Sun, indicating that it may also have been ejected from the lunar surface after a large impact. As telescopes become more sensitive to ...
Asteroid - Wikipedia
An asteroid is a minor planet—an object that is neither a true planet nor an identified comet— that orbits within the inner Solar System. They are rocky, metallic, or icy bodies with no atmosphere, classified as C-type (carbonaceous), M-type , or S-type (silicaceous).
Eyes on Asteroids - NASA/JPL
Explore the 3D world of Asteroids, Comets and NEOs. Learn about past and future missions, tracking and predicting orbits, and close approaches to Earth.
Asteroid Fast Facts - NASA
2014年3月31日 · About once a year, an automobile-sized asteroid hits Earth’s atmosphere, creates an impressive fireball, and burns up before reaching the surface. Every 2,000 years or so, a meteoroid the size of a football field hits Earth and causes significant damage to the area.
Asteroid - Orbit, Composition, Shape | Britannica
3 天之前 · Asteroid - Orbit, Composition, Shape: The rotation periods and shapes of asteroids are determined primarily by monitoring their changing brightness on timescales of minutes to days.
What Is an Asteroid? | NASA Space Place – NASA Science for Kids
2025年1月14日 · Asteroids are small, rocky objects that orbit the sun. Although asteroids orbit the sun like planets, they are much smaller than planets. A close-up image of the asteroid Ida taken by NASA's Galileo spacecraft. Image credit: NASA/JPL-Caltech/UCLA/MPS/DLR/IDA. There are lots of asteroids in our solar system.
What are asteroids? | Space
2023年7月28日 · Asteroids are the rocky remnants of material leftover from the formation of the solar system and its planets approximately 4.6 billion years ago. The majority of asteroids originate from the...
Asteroids and Comets | NASA Jet Propulsion Laboratory (JPL)
2 天之前 · These Sun-orbiting wonders are small celestial bodies with varying combinations of ice, rock, and dust. They survived the tumultuous formation of our solar system 4.5 billion years ago, and the sometimes-chaotic aftermath. An asteroid is mostly rock and dust, with some ice in the mix, while a comet is mostly ice, with some rock and dust.
Physical characteristics and composition of asteroids | Britannica
asteroid, Any of the many rocky small bodies that orbit the Sun mainly in a flat ring, the asteroid belt, between the orbits of Mars and Jupiter.