Asteroid

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Known NEAs

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Asteroids are small, rocky objects that orbit the Sun. Unlike planets, asteroids do not have enough mass to have cleared their orbit of other debris. They are a major focus of astronomy and space exploration due to their potential for scientific research, their threat to Earth, and their resources for future space missions. The majority of known asteroids are found in the Asteroid Belt, a region of space located between the orbits of Mars and Jupiter.

Composition and Classification

Asteroids vary widely in size, composition, and location within the Solar System. They are primarily composed of minerals and rock, with some having significant amounts of metal such as iron and nickel. Based on their composition and albedo, asteroids are classified into several types, including C-type (carbonaceous), S-type (silicaceous), and M-type (metallic).

Discovery and Observation

The first asteroid, Ceres, was discovered in 1801 by Giuseppe Piazzi. Since then, hundreds of thousands of asteroids have been discovered, many through dedicated asteroid survey projects. Modern observations are conducted using both ground-based telescopes and space-based telescopes, with missions such as NEOWISE and OSIRIS-REx providing valuable data.

Impact on Earth

Asteroids have played a significant role in Earth's history, with impacts causing significant changes to the environment and climate. The most famous asteroid impact is the one that is believed to have led to the extinction of the dinosaurs 65 million years ago. Today, the potential threat of an asteroid impact is taken seriously, with various space agencies around the world monitoring near-Earth objects (NEOs) and developing potential mitigation strategies.

Exploration

Several space missions have been launched to study asteroids up close. Notable missions include NASA's Dawn mission, which explored Vesta and Ceres, and the Hayabusa2 mission by JAXA, which returned samples from the asteroid Ryugu. These missions provide invaluable insights into the early Solar System and the materials that formed planets.

Economic Potential

Asteroids are considered to be valuable for their potential mineral and metal resources. The concept of asteroid mining involves extracting these resources for use in space construction and possibly for use on Earth. While still in the conceptual phase, asteroid mining could revolutionize space exploration and the global economy if realized.

See Also

• Comet
• Meteoroid
• Planetary defense