Lecture 12 - Things Go Boom

Question 1

When and how was the universe created?

Answer 1

14 billion years ago, through the big bang

Question 2

How is the life span of a star impacted by it’s size?

Answer 2

The bigger the star, the shorter the life span

- the sun is relatively small, 10 billion year life span

Question 3

Supernova?

Answer 3

Signals the death of a star

Question 4

Solar nebula?

Answer 4

A flattened rotating disk of hydrogen and helium dust, what formed the sun

Question 5

How were the planets formed?

Answer 5

After formation of the sun, orther particles were trapped in orbits attracted other particles until they condensed to form the planets and other objects orbiting the sun

Question 6

Asteroid?

Answer 6

10m-1000 km in diameter, consist of rock, metallic material, or a mix

Question 7

Meteroid?

Answer 7

Smaller pieces of asteroids between dust sized and a few metres across

Question 8

Meteor?

Answer 8

A meteoroid that has entered the earth’s atmosphere, emitting light as it moves

Question 9

Meteorite?

Answer 9

A meteor that strikes the earth

Question 10

Comet?

Answer 10

A rocky core surrounded by ice and covered in dust, has a glowing tail of gas and dust

Question 11

What velocity do extraterrestrial objects enter the atmosphere?

Answer 11

12-72 km/s

Question 12

Airburst

Answer 12

When an extraterrestrial object explodes in the atmosphre

Question 13

Impact

Answer 13

When an extraterrestrial object hits the earth

Question 14

What does an impact crater look like?

Answer 14

• bowl-shaped depression, upraised rim
• rims have an ejecta blanket
• broken rocks cement together into breccia

Question 15

What makes impact craters different than other craters

Answer 15

• involve high velocity and high temperatures

- sends a shock wave, compresses, heats, melts, excavates rock

Question 16

Why are impact craters more common on the moon?

Answer 16

1. most impact sites on earth are in oceans
2. impact craters on land have been eroded or buried
3. smaller objects burn up and disintegrate in earth’s atmosphere

Question 17

What is a simple impact crater?

Answer 17

small (a few km in diameter), do not have an uplift centre

Question 18

What is a complex impact crater?

Answer 18

larger, can be 100 km, rim collapse, the centre of the crater floor rises following the impact
- most impact craters on earth that are larger than 6km are complex

Question 19

What is a mass extinction?

Answer 19

the sudden loss of large numbers of species of plants and animals, classified when >20% of marine genera becomes extinct

Question 20

How many mass extinction events have there been?

Answer 20

5 in the Phanerozoic

• L. Ordovician
• Devonian
• Permian
• Triassic
• Cretaceous (k)

Question 21

What caused the first two extinctions?

Answer 21

global cooling followed by rapid warming

Question 22

What cause the third extinction?

Answer 22

volcanic activity

Question 23

what caused the fourth extinction?

Answer 23

impact of a large asteroid (on the K-T boundary)

Question 24

the fifth extinction is linked to what?

Answer 24

cooling and glaciation

Question 25

What is the 6th extinction event?

Answer 25

RIGHT NOW! because of global warming

Question 26

How did scientists determine the extinction was caused by an impact?

Answer 26

Iridium in clay layers at the KT boundary, fossils below it weren’t found below

Question 27

Where does iridium come from?

Answer 27

Iridium is found in asteroids, meteorites, and in earth’s mantle.

Question 28

Where and when was the KT impact crater found?

Answer 28

1991, the Yucatan Peninsula (30-40km deep)

Question 29

When does an asteroid become a problem?

Answer 29

When it’s path is disrupted by collision, and it leaves the space between jupiter and mars and heads for earth

Question 30

Spaceguard program?

Answer 30

Study near earth objects with a diameter larker than 1km

Question 31

What are our options if a near earth object is on a collision course with earth?

Answer 31

• intercept and blow apart - bad idea

- divert the path of the object - using explosions, much better