Why are meteorite impacts called hypervelocity impacts?

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four impact craters — Meteorite crater Four impact craters of the same size (30 km [20 miles] in diameter) imaged by spacecraft on different solid bodies of the solar system and reproduced at the same scale. They are (clockwise from upper left) Golubkhina crater on Venus, Kepler crater on the Moon, an unnamed crater on Jupiter's moon Ganymede, and an unnamed crater on Mars. The images are oriented such that the craters appear illuminated from the left; the Venusian crater is imaged in radar wavelengths, the others in visible light.

Meteorite impacts are described as hypervelocity impacts because they occur at extreme speeds, typically reaching several tens of kilometres per second. This velocity is many times faster than the speed of sound.1

When an object of sufficient size—generally between 100 metres and several kilometres in diameter—strikes a planetary surface at these speeds, it does not slow down significantly while passing through the atmosphere. The resulting collision releases a massive amount of kinetic energy in a very small area over a short duration. This process is physically more comparable to an atomic bomb explosion than to the simple mechanical displacement of material, as the energy released is often sufficient to vaporize the impacting body entirely.21