Lecture 22

Question 1

Asteroid

Answer 1

Stony or metallic mass that orbits the sun, often within the asteroids belt, with composition of planets, some with own moon, 10^1 to 10^6m

Question 2

Comet

Answer 2

Dirty snowball (rock, dust, CO2, H2O) with tail of dust and gas, and with aphelion outside our solar system, 10^1 to 10^5 m

Question 3

Meteroid

Answer 3

Stony, metallic, or carbonaceous with sun orbit, usually <10m diameter

Question 4

Meteor

Answer 4

The particle or the light due to meteoroid interaction with atmosphere

Question 5

Bolide

Answer 5

A large meteor that explodes in the atmosphere causing an airblast; ‘fireball’

Question 6

Meteorite

Answer 6

Stony (chondrite) or metallic object that landed on Earth

Question 7

Impact structure

Answer 7

Crater, or other evidence of extraterrestrial impact, ‘astrobleme’

Question 8

NEO

Answer 8

Near earth object

Question 9

PHO

Answer 9

Potentially hazardous object

Question 10

Principle sources of comets

Answer 10

Kuiper-bent

Oort cloud

Question 11

Why does earth have the poorest record of impact craters?

Answer 11

Atmosphere causes erosion

Question 12

Why are impacts round?

Answer 12

Due to shear speed object is traveling

Disintegrates

Question 13

Clearwater Canada

Answer 13

2 craters

Probably made by a double asteroid

Question 14

Dating meteor craters

Answer 14

Dating with cosmogenic isotopes
10Be: 49,500 years
36Cl: 49,800 years

Question 15

Chicxulub impact

Answer 15

Yucatan Peninsula
64 million years old
End of dinosaurs
106 miles in diameter

Question 16

Chebarkul Event, 2013

Chelyabinsk Airblast

Answer 16

17m asteroid, 10,000 tons
17km/s
Blast altitude: 15-20 km
Equivalent energy of explosion: 500kT TNT

Question 17

Tuguska Event, Siberia

Answer 17

Aerial explosion of stony asteroid, 25-30m diameter
10mT of TNT, 10 H-bombs
Sound heard over 1 mil km2
Flattened and burned 2000km2

Question 18

Haughton crater

Answer 18

23km wide
1.8km deep
Significant fossil record
Early Miocene assemblage

Question 19

Missing link skeleton

Answer 19

Collected from Haughton crater

Question 20

Associated hazards of large impacts

Answer 20

Earthquake M11
Tsunami 1-3km in height
Wildfires
Nitrous oxides
Dust creates winter
Water vapour and CO2 create greenhouse summer
Extinction

Question 21

Cosmic radiation

Answer 21

Cancer, damage to tissue, damage to electronics
Depends on elevation
Depends on geomagnetic field