The greenhouse effect is the rise in temperature that the Earth experiences because certain gases in the atmosphere (water vapor, carbon dioxide, nitrous oxide, and methane, for example) trap energy from the sun. Normal warming is mostly caused by natural gases.
The main difference between asteroids<span> and </span>comets<span> is their composition, as in, what they are made of. </span>Asteroids<span> are made up of metals and rocky material, while </span>comets<span>are made up of ice, dust and rocky material. Both </span>asteroids<span> and </span>comets<span> were formed early in the history of the solar system about 4.5 billion years ago.</span>
