Asteroids are fascinating celestial objects, often referred to as “minor planets” or “planetoids.
Asteroids are remnants from the early formation of the solar system, around 4.6 billion years ago. They are made of materials that never coalesced into planets.
Most asteroids are found in the Asteroid Belt between Mars and Jupiter, where millions of them orbit the Sun.
Asteroids are composed of various materials:
Rich in carbon, the most common type (75% of known asteroids).
Made of silicate and nickel-iron.
Dominated by metallic iron and nickel.
They range in size from tiny dust particles to large objects like Ceres, the largest asteroid, with a diameter of about 940 km.
Smaller asteroids are often called meteoroids if they’re less than 1 meter across.
Near-Earth Asteroids (NEAs)
Some asteroids come close to Earth. These are categorized as Near-Earth Objects (NEOs) and are monitored for potential collision risks.
Asteroid impacts have shaped planetary surfaces, including Earth’s. A large asteroid impact 66 million years ago contributed to the extinction of the dinosaurs.
Space missions, such as NASA’s OSIRIS-REx to Bennu and Japan’s Hayabusa2 to Ryugu, have studied and returned samples from asteroids.
Some asteroids contain valuable metals like gold, platinum, and rare Earth elements, making asteroid mining a potential future industry.
These share an orbit with a planet, such as Jupiter Trojans, which orbit ahead of or behind Jupiter.
Organizations like NASA track potentially hazardous asteroids (PHAs) to assess their risk to Earth. One such asteroid, Apophis, will make a close flyby in 2029 but is not expected to collide with Earth.
