Meteoroids are fragments of asteroids or comets that enter a planet's atmosphere at hypervelocity, typically between 11 and 72 km/s. Most burn up completely as glowing "shooting stars" around 80-120 km altitude, but larger, denser fragments (especially iron-nickel meteorites) can survive to strike the surface. On airless or thin-atmosphere worlds, essentially every impactor reaches the ground at full speed, so the kinetic energy is converted almost instantly into heat, a shockwave, and ejected debris. The resulting crater is typically 10-20 times wider than the impactor itself due to this explosive energy release, and small craters form simple bowl shapes while larger ones develop central peaks as the ground rebounds.

• Typical atmospheric entry speeds: 11-72 km/s (25,000-160,000 mph)
• Most meteors vaporize around 80-120 km altitude before ever reaching ground
• Crater diameter is roughly 10-20x the impactor's diameter for hypervelocity impacts
• Barringer/Meteor Crater, Arizona: ~1.2 km wide, formed ~50,000 years ago by a ~50 m iron meteorite
• Chicxulub impactor: ~10 km wide, struck 66 million years ago, ended the age of dinosaurs
• Impact energy is released as heat, a radial shockwave, and a curtain of ejecta/debris
• Simple bowl-shaped craters form at small scale; complex craters with central peaks form at larger scale
• Crater rims form from compressed and overturned rock thrown outward during excavation