and in mass extinctions of life on Earth. Asteroid Impacts You need to know the evidence for the dramatic effects that asteroid impacts have had in shaping the surface of planets and their moons and in mass extinctions of life on Earth.

Asteroid Small rocky or metallic body that orbits the Sun. Hundreds of thousands of asteroids exist in the solar system. Asteroids range in size from a few meters to over 500 km (300 mi) wide.

Artist rendition of asteroid impact

Artist's concept of a catastrophic asteroid impact with the early Earth . An impact with a 500-km-diameter asteroid would effectively sterilize the planet. The Earth may have experienced such gigantic impacts in its youth, but fortunately today there are no projectiles this large to threaten our planet

Dino Killer

Dino Killer A large body of scientific evidence now exists that support the hypothesis that a major asteroid or comet impact occurred in the Caribbean region at the boundary of the Cretaceous and Tertiary periods in Earth's geologic history.

Dino Killer Such an impact is suspected to be responsible for the mass extinction of many floral and faunal species, including the large dinosaurs, that marked the end of the Cretaceous period.

Dino Killer Until now, the remains of such an impact crater have escaped detection. The geohydrological feature of Northwestern Yucatan, was discovered, and represents a prime candidate for the impact site of a global catastrophic event.

Asteroid Facts Impacts of asteroids have created craters on the moon, mercury and on other bodies in the solar system. Earth has craters but erosion and plate tectonics erase them. Large events may be the cause of many mass extinctions. Impacts create a iridium rich layer of rock that can be found