The cartoonist mispoke. He meant "meteor. From Nasa: "An asteroid is a small rocky object that orbits the Sun. Asteroids are smaller than a planet, but they are larger than the pebble-size objects we call meteoroids. A meteor is what happens when a meteoroid – a small piece of an asteroid or comet – burns up upon entering Earth’s atmosphere, creating a streak of light in the sky. "
The cartoonist mispoke. He meant "meteor. From Nasa: "An asteroid is a small rocky object that orbits the Sun. Asteroids are smaller than a planet, but they are larger than the pebble-size objects we call meteoroids. A meteor is what happens when a meteoroid – a small piece of an asteroid or comet – burns up upon entering Earth’s atmosphere, creating a streak of light in the sky. "