Chapter 6 : Formation of Solar System

Question 1

Formation Theory Property 1

Answer 1

Patterns of motion of the large bodies
- orbit in the same direction and plane

Question 2

Formation Theory Property 2

Answer 2

Existence of two types of planets
- Terrestrial and jovian

Question 3

Formation Theory Property 3

Answer 3

Existence of smaller bodies
- asteroids and comets

Question 4

Formation Theory Property 4

Answer 4

Notable exceptions to usual patterns
- rotation of uranus, earth’s moon

Question 5

nebular theory

Answer 5

states our solar system formed from the gravitational collapse of a giant interstellar gas cloud (solar nebula)

Question 6

why did the solar nebula heat up as it collapsed?

Answer 6

as the cloud shrank, its gravitational potential energy was converted to thermal energy

Question 7

what kind of material in the solar nebula could condense at temperatures as high as 1500 K in the inner region of the nebula?

Answer 7

metals

Question 8

Relevance of nebular theory

Answer 8

-Kant and Laplace proposed nebular hypothesis over two centuries ago
-large amount of evidence now supports this idea

Question 9

Close Encounter Hypothesis

Answer 9

rival idea proposed that the planets formed from debris torn off the sun by a close encounter with another star

Question 10

accuracy of close encounter hypothesis

Answer 10

does not explain observed motions and types of planets

Question 11

Galactic Recycling

Answer 11

Elements that formed planets were made in stars and then recycled through interstellar space

Question 12

nebular theory evidence from other gas clouds

Answer 12

we can see stars forming in other interstellar gas clouds

Question 13

what caused the orderly patterns of motion in our solar system?

Answer 13

conservation of angular momentum and flattening

Question 14

Conservation of Angular Momentum

Answer 14

rotation speed of cloud from which our solar system formed must have increased as the cloud contracted

Question 15

flattening

Answer 15

collisions between particles in the cloud caused it to flatten into a disk
-spinning cloud flattens as it shrinks

Question 16

how do collisions between gas particles effect motions?

Answer 16

-gradually reduce random motions
-reduce up and down motions

Question 17

Why are there two major types of planets?

Answer 17

conservation of energy

Question 18

as gravity causes cloud to contract…

Answer 18

it heats up

Question 19

temp of inner parts of disk

Answer 19

hotter than other parts

Question 20

rock remains solid at…

Answer 20

greater temps then ice

Question 21

inside the frost line

Answer 21

too hot for hydrogen compounds to form ices

Question 22

outside the frost line

Answer 22

cold enough for ices to form

Question 23

how did terrestrial planets form?

Answer 23

• small particles of rock and metal were present inside frost line
• planetesimals of rock and metal built up as these particles collided

Question 24

how did gravity change the planetesimals?

Answer 24

-assembled planetesimals into terrestrial planets

Question 25

accretion, process of assembly

Answer 25

-draws planetesimals together to form planets

Question 26

how did jovian planets form?

Answer 26

-ice could form small particles outside frost line
-larger planetesimals and planets were able to form

Question 27

how did gravity affect jovian planets?

Answer 27

-gravity of larger planets and rock and ice was able to draw in surrounding H and He gases

Question 28

Where are the leftover gases?

Answer 28

a combination of photons and solar wind, outflowing matter from sun, blew away the leftover gases

Question 29

Solar rotation over time

Answer 29

in nebular theory, young sun rotated much faster than now
- friction between solar magnetic field and solar nebular thought to have slowed rotation over time

Question 30

where did asteroids and comets come from?

Answer 30

Leftovers from accretion process
- heavy bombardment

Question 31

where are rocky asteroids?

Answer 31

inside frost line

Question 32

where are icy comets?

Answer 32

outside frost line

Question 33

origin of earth’s water

Answer 33

water may have come to earth by icy planetesimals

Question 34

captured moons

Answer 34

unusual moons of some planets may be captured planetesimals

Question 35

why does our moon exist?

Answer 35

giant impact

Question 36

odd rotations explanation

Answer 36

giant impact

Question 37

how would the solar system be different if the solar nebula had cooled with a temperature half its actual value?

Answer 37

jovian planets would have formed closer to the sun

Question 38

which of these facts is not explained by the nebular theory?
a. 2 main types of planets
b. planets orbit in same direction and plane
c. existence of asteroids and comets
d. number of planets of each type

Answer 38

d. number of planets of each type

Question 39

considering only the tilt of their axis, which planet would have the most extreme seasons?

Answer 39

uranus

Question 40

how do we explain “exceptions to the rules”?

Answer 40

bombardment of newly formed planets by planetesimals may explain the exceptions

Question 41

how do you measure the age of a rock?

Answer 41

-some isotopes decay with a well-known half life
-comparing proportions of those isotopes with decay products tells us the age

Question 42

how do we know the age of the solar system?

Answer 42

-radiometric dating of meteorites indicates planets formed 4.5 billion years ago

Question 43

plasma

Answer 43

consists of gas in which many or most of atoms are ionized (missing electrons)

Question 44

what happens to energy in the sun’s convection zone?

Answer 44

energy is transported outward by the rising of hot plasma