Three Related Terms
A meteoroid is a small rock or metal fragment in space. When it enters the atmosphere and glows, the visible phenomenon is a meteor. If surviving material reaches the ground, it is a meteorite.
Core picture: meteor light is not ordinary flame. It comes from high-speed atmospheric entry, compression, heating, ablation, and ionization.
Why Speed Matters
Meteoroids often enter the atmosphere at tens of kilometers per second. Kinetic energy scales with speed squared, so even a small object can release a large amount of energy in a short time. The atmosphere is a medium that can be compressed and heated violently.
"Friction" Is Only a Shortcut
People often say meteors glow because of air friction. The fuller explanation is that air in front of the object is compressed and heated by a shock wave; the surface melts, vaporizes, and sheds material into the wake.
Hot gas and ionized atoms then emit light, producing the bright streak.
Why Some Meteors Become Fireballs
Brightness depends on mass, speed, entry angle, material strength, and fragmentation. A larger object can break apart in the atmosphere, suddenly increasing heated surface area and producing a bright fireball. Strong fragments that survive ablation can become meteorites.