What is the primary composition of asteroids compared to comets?

The primary composition of asteroids is mostly rock and metal, which makes them distinct from comets. Asteroids primarily reside in the asteroid belt between Mars and Jupiter and are remnants from the early solar system. They typically consist of silicate minerals and metals such as nickel and iron, which contribute to their solid and rocky structure.

In contrast, comets are known for their icy composition, which includes significant amounts of water ice, carbon dioxide, ammonia, and other volatile compounds. When comets approach the Sun, the heat causes these ices to sublimate, creating a glowing coma and tails made up of gas and dust.

Understanding this composition difference helps clarify the distinct roles asteroids and comets play in the solar system. While asteroids are often categorized as "the building blocks of planets" due to their rocky nature, comets are often referred to as "dirty snowballs" because of their icy makeup. This distinction underscores the different terrains and conditions these celestial bodies represent within the solar system.