Meteors do burn up when they enter Earth's atmosphere. The friction between the meteor and the air molecules causes the meteor to heat up and glow, creating a streak of light in the sky. This process is called ablation.

The amount of ablation that occurs depends on the size, speed, and composition of the meteor. Smaller meteors are more likely to burn up completely, while larger meteors may only partially burn up. Meteors that enter the atmosphere at a higher speed are also more likely to burn up completely.

The composition of the meteor also plays a role in how much ablation occurs. Meteors that are composed of more volatile materials, such as ice or organic matter, are more likely to burn up completely than meteors that are composed of more refractory materials, such as rock or metal.

In general, most meteors that enter Earth's atmosphere are completely burned up before they reach the ground. However, a few larger meteors may survive the ablation process and impact the Earth's surface. These meteors are called meteorites.