Extinction

Question 1

What was the Chelyabinsk Meteor in 2013?

Answer 1

Small asteroid travelling about 20x faster than a speeding bullet!
- Entered Earth’s atmosphere and exploded
- People in Chelyabinsk could feel the heat from the fireball as well as the shock wave from the explosion
- Meteor did not impact Earth

Question 2

How did the Chelyabinsk Meteor do damage?

Answer 2

No one knew it was coming before explosion
- More than 7000 buildings damaged
- 1500 people required medical attention
- Broken windows in homes

Question 3

What is Earth’s place in space?

Answer 3

Origin with the Big Bang 14 billion years ago; explosion producing atomic particles.
First stars formed 13 billion years ago

Question 4

What is a supernova? What is its significance to us?

Answer 4

Death of a star; explosion scatters mass into space creating a nebula.
5 billion years ago, a supernova explosion triggered the formation of our sun.
Sun grew by buildup of matter from solar nebula

Question 5

How do planets form?

Answer 5

Particles in rings attracted other particles and collapse into planets.
Earth was hit by objects that added to its formation.
Bombardment continues today at a lesser rate.

Question 6

What are asteroids vs. meteors vs. comets?

Answer 6

Asteroid: found in asteroid belt between Mars and Jupiter. Composed of rock, metallic compounds, or combinations of these. They’re HUGE.
METEOROIDS are BROKEN UP asteroids.
Meteor: meteoroids that enter earth’s atmosphere. They burn and create “shooting stars”. Very very tiny like dust.
Comet: has a glowing tail. Composed of rock surrounded by ice. They’re a few meters to a few hundred meters large.

Question 7

How are particles in our solar system arranged?

Answer 7

By diameter and composition

Question 8

What is the Kuiper Belt?

Answer 8

Surrounds all of the planets in our solar system

Question 9

What do meteors do?

Answer 9

They either explode into an airburst (Chelyabinsk), or they collide with Earth as a meteorite. Concentrated in Antarctica.

Question 10

What are impact craters?

Answer 10

They provide evidence of Meteor impacts. Example is the Barringer Crater in Arizone. The broken rocks cemented together into Breccia

Question 11

What are the features of impact craters?

Answer 11

Involve high velocity, energy, pressure and temperature. The kinetic energy of impact produces shock wave to Earth. Rocks become metamorphosed or melt with other materials.

Question 12

What are the two types of impact craters?

Answer 12

1. Simple craters: typically small (< 6 km), like the Barringer Crater, looks like moon craters
2. Complex Impact Craters: large in diameter (> 6 km), rim collapses more completely, center uplifts following impact

Question 13

What is catastrophism?

Answer 13

Those studying the formation of mountains, large river valleys, and other features had a hard time understanding how they could be formed in 6000 years.

Question 14

What is Gradualism or Uniformitarianism?

Answer 14

James and Charles Hutton invented it
Says that present geological processes may be studied to learn the history of the past
Argues that Earth must be much older than 6000 years

Question 15

What is punctuated Uniformitarianism?

Answer 15

Athough uniformitarianism explains the long geologic record of gradual
mountain building, canyon erosion, and landscape construction, periodic
catastrophic events do occur and can cause mass extinctions.

Question 16

What are mass extinctions?

Answer 16

Sudden loss of large numbers of plants and animals, relative to number of new species being added.
Defines the boundaries of geologic periods of epochs.

Question 17

What causes mass extinctions?

Answer 17

Usually involve rapid climate change, triggered by:
- Plate tectonics (slow process that moves habitats to different locations)
- Volcanic activity
- Extraterrestrial impact or airburst

Question 18

What are the 6 major mass extinctions?

Answer 18

1. Ordovician, 446 mya; continental glaciation in Southern Hemisphere
2. Permian, 250 mya; colvanoes causing global warming and cooling
3. Triassic-Jurassic boundary, 202 mya; volcanic activity associated with the breakup of Pangaea
4. Cretaceous-Paleogene boundary (K-pg boundary), 65 mya; asteroid impact
5. Eocene period, 34 mya; plate tectonics
6. Pleistocene Epoch, initiated by airburst, continues today caused by human activity

Question 19

Discuss the K-Pg Boundary Mass Extinction.

Answer 19

Dinosaurs disappeared with many plants and animals.
- 70% of all genera died
- Set the stage for evolution of animals
A clay layer formed quickly
Probably extinction caused by single asteroid impact (crater)

Question 20

What were the sequence of events for the K-Pg mass extinction?

Answer 20

a) Asteroid moving at 30km/second.
b) Asteroid impacts Earth, producing a crater 200 km wide and 40 km deep; shock waves crush, melt rocks, vaporized rocks on outer fringe.
c) Seconds after impact, ejecta blanket forms; mushroom cloud of dust and debris; fireball sets off wildfires around the globe; sulfuric acid enters atmosphere; dust blocks sunlight; tsunamis from impact reach over 1000 feet
d) Months after impact, no sunlight; no photosynthesis; continued acid rain; food chain stopped
e) Several months after impact, sunlight returns; acid rain stops; ferns restored on burned landscape

Question 20

How are asteroids/comets/airbursts linked with other natural hazards?

Answer 20

Direct cause for:
- Tsunamis (impacts ocean)
- Wildfires (superheated clouds of gas make things dry)
- Earthquakes (seismic waves created)
- Mass Wasting (earthquakes = landslides)
- Climate Change (lots of dust, causes cooling then warming)
- Volcanic Eruptions (impacts cause melting and instability in Earth’s Mantle)

Question 20

How can we minimize the impact hazard of these space things?

Answer 20

Identify nearby threatening objects
Spacewatch
Near-Earth Asteroid Tracking (NEAT) project
Use telescopes and digital imaging devices

Question 21

How do we get rid of space threats once they’re detected?

Answer 21

a) Blow it up in space
b) Nudge it out of Earth’s orbit
c) Evacuation

Question 21

Discuss the Chelyabinsk Meteor again.

Answer 21

• Largest known asteroid to have entered Earth’s atmosphere since Tunguska event
• Hit a lake, but could’ve been worse if it hit the ground or hit an urban area (many deaths)