Lecture 5

Question 1

What is a meteorite?

Answer 1

Fragments of rock from interplanetary space which entered in collision with a planet

Question 2

Where do meteorites come from?

Answer 2

Asteroid collisions

Question 3

What are the 3 subdivisions of meteorites?

Answer 3

Chondrites, Iron, and Stony-Iron

Question 4

What are chondrules?

Answer 4

Quasi-spherical structures which indicate solidification from molten droplets splashed during collisions between various celestial bodies.

Question 5

What are chondritic meteorites?

Answer 5

The most frequent ones, silicate dominated.

Question 6

What are iron meteorites?

Answer 6

Meteorites which present large sized crystals-indicating a longer time of solidification.

Question 7

What are stony-iron meteorites?

Answer 7

Silicates and iron-nickel alloys occur in approximately equal proportions-RAREST

Question 8

What are the 3 categories of silicate dominated (chondritic) meteories?

Answer 8

Achondritic-do not have chondrites
Carbonaceous chondrites- have organic matter that make it shiny
Chondrites

Question 9

What is special about carbonaceous chondrites?

Answer 9

They have amino acids as organic matter (not the same amino acids as ones that are the building blocks of life).

Question 10

Why did dating of meteorites prove to be perplexing?

Answer 10

Because they are around 4.6 billion years old, which is exactly the same age as the basalts from the moon.

Question 11

What do the lines on Phobos represent?

Answer 11

Parts of mantle of old celestial bodies that broke apart

Question 12

What are comets?

Answer 12

Celestial bodies consisting mostly of frozen gases. (CO2, NH3, CH4, CO, H2O).

Question 13

What creates the tail on a comet?

Answer 13

Formation of gases that are still attached to the body of the comet, but rotating the opposite way.

Question 14

What is space dust?

Answer 14

Small particles that can pass through the atmosphere. Exits in both interstellar and interplanetary space.

Question 15

What makes the study of space dust so difficult?

Answer 15

It’s easily contaminated and we don’t know when it was contaminated

Question 16

What is space dust made of?

Answer 16

C, Mg, Fe, and Ca-makes it solid

Question 17

What is the name of the machine that can collect space dust for us to study?

Answer 17

Galileo

Question 18

What was the most important finding from space dust?

Answer 18

It’s dominant oxygen isotope is O17, whereas the dominant isotopes on Earth are O16 and 18. Concludes that there could be life outside of our galaxy.

Question 19

What is the Solar Nebula Theory?

Answer 19

Theory that was developed in the 2nd half of the 18th century, beginning as a mathematical model, that explains the formation of the solar system in 6 stages

Question 20

What is Phase 1 of the solar nebula theory?

Answer 20

Contracting Cold Cloud. Huge cloud of gases and cosmic dust begins to contract (dominant process) and rotate slowly. Composition of this cloud was mostly H and He

Question 21

What is Phase 2 of the Solar Nebula Theory?

Answer 21

Rotating and Heating Cloud: Rotation became dominant, cloud became lens shaped, discoidal, and rotated FASTER. Matter then started to concentrate and heat in the centre of the cloud.

Question 22

What is Phase 3 of the Solar Nebula Theory?

Answer 22

Chaotic Swirling and Incipient Accretion: Small sized particlesof cloud aggregated to form larger (irregularly shaped) rock particles. Source for turbulent movements. Caused cloud to also be concentrated in the rings around it, not only in the centre

Question 23

What is Phase 4 of the Solar Nebula Theory?

Answer 23

Formation of Protoplanets: Larger, but with reduced gravity. Matter started to collapse due to gravitational attraction, initiating process of gravitational differentiation (iron towards centre, silicate towards periphery).

Question 24

What was the cause of the Protosun (phase 4)

Answer 24

Gravitationally controlled matter compression

Question 25

What is Phase 5 of the Solar Nebula Theory?

Answer 25

Birth of Sun: Initiation of thermonuclear reactions resulting in ignition. Energy was dissipated in the solar wind. Planets with smaller masses could not retain lighter elements as part of their atmosphere (except for Jovian planets).

Question 26

What is Phase 6 of the Solar Nebula Theory?

Answer 26

Major Collisions and Readjustments: Large number of planets existed and collisions started, creating the meteorites. Also collided with Earth, which vaporized the oceans and sterilized Earth’s surface.