Meteoroids speed up as they approach Earth primarily due to the planet's gravitational pull, which intensifies as the distance decreases.

Gravitational Acceleration

Earth's gravity acts like an invisible hand, pulling the meteoroid faster and faster the closer it gets. In space, far from any strong gravity, the meteoroid might drift at a relatively steady pace from its solar orbit—often around 20-30 km/s relative to Earth. But once within Earth's gravitational sphere (roughly starting hundreds of thousands of kilometers out), Newton's law of universal gravitation kicks in: the force F=GMmr2F=G\frac{Mm}{r^2}F=Gr2Mm​ grows stronger as separation rrr shrinks, converting potential energy into kinetic energy and boosting speed by up to 11 km/s or more.

This isn't just a gentle tug; picture a roller coaster dropping from a high peak—the meteoroid "falls" toward Earth, accelerating until it hits the thin outer atmosphere.

Role of Initial Orbit

Meteoroids aren't dropped from rest; they carry high baseline speeds from orbiting the Sun, similar to Earth's 30 km/s path. Depending on approach angle:

  • Head-on collisions (morning sky side) add Earth's orbital speed to the meteoroid's, hitting 70+ km/s.
  • Trailing approaches (evening sky) are slower but still accelerate via gravity.

No significant drag exists in the vacuum of space, so nothing slows this buildup until atmospheric entry.

Atmospheric Entry Dynamics

Only after speeding up does the meteoroid slam into the atmosphere at 11-72 km/s, where compression heats air ahead of it to glowing plasma (creating the shooting star). Larger ones punch through without fully slowing; smaller ones vaporize. But the speedup? Purely gravity's doing before that fiery plunge.

TL;DR: Gravity pulls harder up close, accelerating the meteoroid like a stone in freefall—until air resistance takes over.

Information gathered from public forums or data available on the internet and portrayed here.