These objects could kill millionsof people, but the damage is not greater than that from other natural events such as earthquakes. At time periods approaching one hundred million years, mountain-sized comets and asteroids with diameters near 10 km will hit Earth. When a 10 km sized object hits the surface it creates an enormous ejecta cloud which explodes outward into space, and reenters the atmosphere as countless shooting stars. The sky would be converted from its normal transparent blue to a brilliant red sheet of glowing lava. Smoke from fires, dust from pulverized ejecta, and sulfate from within the objects would cause so much light loss that photosynthesis would cease for several months, a likely mechanism for causing extinctions in the ocean.
Land surface temperatureswould also plummet.
Pity the poor dinosaurs, to whom this happened. Impact Hazard A meteoroid does not have to reach the ground to cause damage. Man made satellites orbiting as far as 35,000 kilometers above the earth farther, can easily be damaged by a small meteoroid. Even the shuttle experiences minor damage from micro-meteroids every mission. Each day as many as 4 billion meteoroids, most miniscule in size, enter earth's atmosphere.