Lecture Thirty Two - Asteroids, Meteors and Meteorites Flashcards
What are asteroids, meteors and meteorites?
Left overs from solar system formation. Either planets that didn’t fully form, or fragments of planets that were shattered.
Fragmented smaller bodies.
Pieces of other rocky planets, eject by impacts.
Anything rocky that falls to Earth.
Define meteor, meteoroid, meteorite, asteroid and comet.
Meteor - the flash of light caused by an object that burns up in the earths atmosphere.
Meteoroid - any object smaller than 1km that enters the earth atmosphere. Most burn up before they reach the surface.
Meteorite - meteoroid that survives the fall to earth.
Asteroid - large rocky or icy body, most found in the asteroid belt between Mars and Jupiter (inner solar system).
Comet - icy body, mostly come from the Oort cloud on the edge of the solar system (outer solar system).
How many of these bodies are there?
It depends on the size of the object.
The larger the body is, the fewer there are.
How do these bodies get to Earth?
Gravity …
Attracted by the earths gravity,
Or
Pushed in out direction after an encounter with another planet.
Or
Attracted by the Suns gravity and the Earth gets in the way.
Or
Left behind by comets - most meteor showers.
What happens when one of these bodies reaches the earth?
Most burn up in the earths atmosphere.
Traveling at high speeds.
Many variables - how big is it, what is it made of, how fast does it hit, what angle does it hit, where does it hit.
What relevance do these bodies have in mass extinctions?
Many mass extinction have some connection to asteroid or comet impacts.
Asteroid impacts release clouds of dust and smoke ingot he atmosphere, this kills plants for years and leads to food shortages and can push planet into an ice age.
What is the probability of being killed by an asteroid?
If we do get hit by an object, it will likely land in the ocean (greater proportion of Earth is ocean).
1 in 3500 chance that you specifically will be hit.
Odds of you specifically getting killed by an asteroid is bout 1 in 25,000.
How many fatalities would be experienced after an impact?
Not all deaths would be directly due to the impact.
An impact could cause food shortages, cool the planet, therefore more deaths would be due to starvation and war.
What is the cost of prediction of impacts?
Very expensive to watch skies.
How can impacts be avoided?
Nudge it into a different orbit - the earlier the nudge ,the easier it will be and the less it needs to be nudged.
Nuclear explosion near object.
Attach a rocket to the object.
Slam something into the object.
Focus sun onto it to vaporise part of it.
Park a large object next to it (gravitational pull).
