Asteroids (Minor Planets)
Asteroids are rocky, airless remnants left over from the early stages of the solar system. Scientists believe they are the fragments of a planet that tried to form but never fully coalesced due to the overwhelming gravitational interference of Jupiter.
1. Location and Distribution
While asteroids can be found scattered throughout space, the vast majority are concentrated in specific regions:
- The Main Asteroid Belt: The largest reservoir of asteroids, forming a massive ring orbiting the Sun exactly between the orbits of Mars and Jupiter.
- Trojans: Asteroids that share an orbit with a larger planet (most notably Jupiter), caught in the planet’s gravitational balance points.
- Near-Earth Asteroids (NEAs): Asteroids whose orbits cross or come dangerously close to Earth’s orbit. These are closely monitored by space agencies for potential planetary defence.
2. Characteristics and Classification
Asteroids completely lack an atmosphere. Because of their small size, their gravity is too weak to pull them into perfect spheres, leaving them with highly irregular, potato-like shapes. They are classified into three broad types based on their chemical composition:
- C-type (Carbonaceous): These are rich in carbon, visually very dark, and represent the most common type of asteroid (accounting for about 75% of known asteroids).
- S-type (Salicaceous): These contain silicate materials and nickel-iron (accounting for roughly 17%).
- M-type (Metallic): These are composed almost entirely of solid nickel and iron.
