Asteroids
Rocky Remnants of the Early Solar System
Asteroids are rocky objects that orbit the Sun, mostly found in the asteroid belt between Mars and Jupiter. They are remnants from the early solar system, dating back 4.6 billion years. Some asteroids have moons of their own.
Key Facts About Asteroids
- Number Known: Over 1.3 million identified
- Largest: Ceres (940 km diameter, also a dwarf planet)
- Main Belt Location: Between Mars and Jupiter (2.2-3.2 AU)
- Composition: Rock, metal, or a combination
- Total Mass: Less than 4% of the Moon's mass
Near-Earth Asteroids
Some asteroids have orbits that bring them close to Earth. These Near-Earth Asteroids (NEAs) are monitored closely. NASA's planetary defense efforts include tracking these objects and developing missions to deflect potentially hazardous ones.
Asteroid Mining
Asteroid mining is a concept being explored by several companies. Some asteroids contain valuable metals like platinum, gold, and rare earth elements. A single metallic asteroid could contain more resources than have ever been mined on Earth.