What are asteroids and comets, and where do they come from?
- meteor - dust to cm size
- meteoroid - cm to 10m diameter
- asteroid - > 10 m diameter and rocky
- comet - ice and rock
What is the velocity of asteroids and comets and how fast can they hit the earth?
- velocity is cosmic - 12-72 kps
- 300-600 seconds
What are your odds of getting eliminated in an asteroid impact event?
less than of dying in an airplane crash
What are the 3 major extinction events that have happened in the past?
- 1) cretaceous period, did in dinosaurs, 80% of all life, 65 million years
- 2) permian period, 245 million years, 95% of all marine life
- 3) devonion period, 320 million, 70% of all marine life
What eliminated the dinosaurs and how big was the object?
the chicxulub asteroid that was 180km
How many objects do they think are out there that can threaten the earth?
- about 1700 serious ones that could end life and civilization
- potentially millions of smaller ones that would do regional damage
What are we doing about it as a global society?
in planning stage of an asteroid deflection program
Where would an impact likely take place and what would happen?
- 70% chance of hitting in oceans
- large 3000ft tidal waves
How many scientists are now actively looking for Earth-crossing asteroids and comets?
two dozen full-time people worldwide
Why are the impact events of the past evident on the moon and not the earth?
earth gets hit just as much as the moon but the moon doesn't have an atmosphere to get rid of most of it before impact
What can you do about this threat personally?
pressure government to support space program and asteroid watch programs
region between orbits of mars and jupiter that contains most of the large rock or metallic particles in our solar system
- spherical shell that lies beyond kuiper belt and extends out as far as 50,000 times the distance from the earth to the sun
- home to the comets
- region extending from neptune, beyond the planets
- larger than asteroid belt and comprised mostly of frozen volatiles
- largest impact event on or near earth in recorded history
- asteroid burst in the air over russia in 1908
Space Watch / Spaceguard
- both are search programs
- spaceguard is US
- spacewatch is international
- lincoln near earth asteroid research
- funded by US
- formed 49,000 years ago from 50m impactor
- origin established by gene shoemaker in 1950s