The Solar System

Question 1

What is a star?

Answer 1

Generates energy via nuclear fusion-emits mostly black body radiation that depends on its temperature

Question 2

Why does a planet shine?

Answer 2

Reflected light

Question 3

What are conditions of a solar system planet?

Answer 3

•orbits sun
•massive enough that it’s gravity causes it to be spherical
•has largely cleared its neighbourhood of other bodies

Question 4

What is orbital plane of planets like?

Answer 4

Close to ecliptic(5 degrees)
(Pluto 17)

Question 5

What is typical eccentricity of planets?

Answer 5

<0.05 (Pluto 0.25)

Question 6

Steps of formation of solar system

Answer 6

1. An interstellar cloud collapses under gravity
2. Centrifugal force causes gas cloud to flatten into a protostellar or protoplanetary disk
3. Gas piles up in centre, increasing in density & temperature, starts nuclear fusion: star is born
4. In protoplanetary disk, dusk grains collide, stick, and aggregate into planetesimals
5. Planetesimals collide and grow into planets, clearing their orbit
6. Nearby planets have gas evaporated by sun, can’t hold onto moons; distant bodies keep their cold gas, have many moons

Question 7

What are mars moons called?

Answer 7

Phobos and Deimos

Question 8

How many moons does Jupiter have?

Answer 8

79 (4 large Galilean moons)

Question 9

How many moons does Saturn have?

Answer 9

82 (1 large called Titan)

Question 10

How many moons does Uranus have?

Answer 10

27

Question 11

How many moons does Neptune have

Answer 11

14 (Triton large backwards orbit)

Question 12

How are Jovian planet rings kept in place?

Answer 12

Small shepherd moons

Question 13

What are rings made up of?

Answer 13

Small grains of ice and dirt

Question 14

Describe asteroids

Answer 14

•small rocky bodies
•generally few km in size
•Irregular shapes

Question 15

Which planets is the asteroid belt between?

Answer 15

Mars and Jupiter

Question 16

Describe Comets

Answer 16

•small ball of ice and dust that orbit sun
•highly elliptical orbits
•dust tail and ion tail

Question 17

What happens as comets approach sun?

Answer 17

Temperature increases and gas and dust evaporate off comet (Coma)

Question 18

What is the dust tail?

Answer 18

Radiation pressure blows off dust

Question 19

What is the ion tail?

Answer 19

Solar wind blows off ionized plasma

Question 20

Describe Kuiper Belt?

Answer 20

•ring of material, 30-100 AU from sun
•10^5 bodies bigger than 100km
•short period comets
•Pluto and eris

Question 21

Describe Oort Cloud?

Answer 21

•cloud of material extending to about 50000AU from sun
•may contain a trillion objects
•long period comets

Question 22

What are meteor showers?

Answer 22

•comets leave a wake of large pebble sized particles
•earth passes through a comets orbit, particles produce meteor shower

Question 23

What is a meteor?

Answer 23

When a body burns up in atmosphere
4 billion per day

Question 24

What is a meteorite?

Answer 24

If a body hits the ground. Typically moving at 10km/s when they strike ground

Question 25

Impact rate and effect

Answer 25

•hourly: <1m sized bodies burn up in atmosphere (shooting stars)
•yearly: 1-100m bodies small craters/atmospheric explosion
•every million years: km sized bodies tsunamis/ widespread destruction
•every hundred mill years: 10-100km sized bodies, mass extinction

Question 26

What is a primitive meteorite?

Answer 26

•remnants from the birth of solar system

Question 27

What is a processed meteorite?

Answer 27

Once part of a larger object that has processed the primitive material