Activity 4- Impact Events and the Earth System

Barringer Crater – Northern AZ The world’s best preserved meteorite impact site on Earth. Meteor Crater is the breath-taking result of a collision between an asteroid traveling 26,000 miles per hour and planet Earth approximately 50,000 years ago. Meteor Crater is nearly one mile across, 2.4 miles in circumference and more than 550 feet deep. www.meteorcrater.com

Asteroids Rocky bodies left over from formation of the solar system Orbit the sun – very eccentric orbits Asteroids >1km hit the Earth every few hundred million years

Asteroids Ceres (the largest- 950 Km across) is classified as a dwarf planet It is widely believed that an asteroid caused extinction of the dinosaurs NASA is currently working on a mission to have an astronaut walk on an asteroid!

NASA Near Earth Objects watch

Torino Scale Scale 1-10 1 = little effects 10 = catastrophic effects Measures the effects of an impact Scale 1-10 1 = little effects 10 = catastrophic effects

Comets Dirty snowball! Frozen gas and dust Orbits are very eccentric and have a high inclination Have two tails, the gas tail (blue) and the dust tail (white) Famous periodic comet- Halley’s Comet (July 28, 2061 next perihelion)

Halley’s Comet Passes by Earth every 75 years Next approach July 28, 2061 – mark your calendars! 10 miles long, 5 miles wide and 5 miles high

Anatomy of a Comet Tail always faces AWAY from the sun Coma – cloud of dust and gas Nucleus – center of the comet

Meteoroids, Meteors, and Meteorites Named for where they are: A meteoroid is in space A meteor is passing through the Earth’s atmosphere (shooting star) A meteorite is found on Earth