Final answer:
Comets are mostly made of ices, while asteroids are primarily rocky. Comets often form a glowing atmosphere and tail when near the Sun due to their icy nature, whereas asteroids, being composed of rocks and metals, retain little volatile material.
Step-by-step explanation:
Comets and asteroids are components of our solar system, each with distinct compositions and characteristics. The main answer to what comets and asteroids are primarily composed of is: comets are mostly composed of ices, while asteroids are mainly composed of rocks.Explanation in more than 100 words: Comets are often referred to as 'dirty snowballs', as they predominantly consist of frozen water, carbon dioxide, ammonia, and methane, mixed with dust particles. When a comet approaches the Sun, its icy composition heats up, creating a glowing coma (temporary atmosphere) and sometimes a tail that stretches for millions of kilometers. On the other hand, asteroids are composed of various rocks and metals, and retain little volatile material. They are typically found in the asteroid belt between Mars and Jupiter and can vary in size from small boulders to objects hundreds of kilometers in diameter. Asteroids tend to retain their original composition and thus are akin to 'chemical fossils' that provide insights into the early solar system.Conclusion: Therefore, option 1 is correct; comets are mostly made of ices, and asteroids are primarily rocky.