Chapter 7: The Solar System

Question 1

Beginning formation of solar system

Answer 1

• nebula initially (pre-stellar nebula) (pre solar nebula)
• star is forming in centre but lots of material in disk outside in which planets form
• pressure from star turning on sweeps has out of orbit
• 100 million years later the solar system was fully formed

Question 2

Aggregation

Answer 2

Rocky planetesimals formed from pieces sticking together

-like making a snow man

Question 3

Differentiation

Answer 3

Different material will form or unform based on how far from the sun it is

Like Earth firms silicates, rocky materials, water
Whereas Saturn has ammonia ice

Question 4

Age of solar system

Answer 4

About 5.6 billion years

Question 5

Composition of solar system

Answer 5

1. Sun
2. Planets (8)
3. Asteroids (asteroid belt)
4. Comets (Oort cloud)
5. Dwarf planets

Question 6

Planets motion

Answer 6

• length of years depends on distance from sun
• pos rotation means same direction as orbit of sun opposite is neg
• most planets are tilted compared to orbit
• inclination to orbital plane as well (Mercury has largest inclination)

Question 7

Terrestrial planets

Answer 7

• Earth, Mar, Venus, Mercury

- rocky, dense, small, few satellites (moons)

Question 8

Mars moons

Answer 8

Phobos and Deimos

Question 9

Jovian planets

Answer 9

• Jupiter, Saturn, Uranus, Neptune
• large, gaseous, low density, many moons
• gas giants

Question 10

Impact craters

Answer 10

• need rocky surface and little atmosphere to survive

- Earth Barringer (1.2 km)

Question 11

Rings

Answer 11

Saturn has very obvious rings, but all the Jovian planets have rings
-no terrestrial planets have rings

Question 12

Comets

Answer 12

• found in Oort belt and Kuiper belt
• most are very far away and can not be observed
• they are distributed in random orbits and are left overs from formation of solar system
• orbits both eccentric and highly inclined
• not very big (1km) but tail can be 1Au

Question 13

Comets composition

Answer 13

-solid core: nucleus make of different ices
-coma: when the ice is evaporating around nucleus
-Tail: always points away from sun due to radiation pressure from sun
(May have 2 tails one from dust which is radiation and has pressure and one from gas)

Question 14

Meteors

Answer 14

• are solid and rocky in composition
• are basically shooting stars, very small particles that skid across the atmosphere and burn up
• mostly due to chunks left from comets passing by

Question 15

Meteroites

Answer 15

• A solid object that actually hits the ground
• Bigger then meteors
• Hoba
• they are either rocky Chondrites or Iron

Question 16

Asteroids

Answer 16

• larger lumps of rocks in space
• usually not spherical, no atmospheres or moons
• most in main asteroid belt between Mars and Jupiter
• didn’t end up making a planet

Question 17

Pluto

Answer 17

• a planetary oddity
• orbit crosses Neptune’s orbit
• highly inclined
• resonant orbit which Neptune 3:2
• more terrestrial (small, no rings, few moons)
• moons: Charon, Hydro, Kerberos, Styx
• Pluto and Charon considered dwarf planet pair

Question 18

Centaurs

Answer 18

Objects found mostly between Saturn and Neptune

-mostly rocky but sometimes have coma and tail

Question 19

Trans Neptunian Objects

Answer 19

Anything past Neptune
-Plutinos: anything near Pluto
-Kuiper belt: broad range
-scatter disk: fewer of them, scattered
         —> Eris: larger then Pluto
-lots of TNOs being discovered

Question 20

Classifying planets

Answer 20

• has to orbit the sun
• is large enough to be round under its own gravity
• has cleared its lane of other material

Question 21

So what is Pluto?

Answer 21

A dwarf planet

• has an orbit
• large enough to be round
• but has not cleared its path

Question 22

-Doppler shifts detection methods

Answer 22

• the star in the middle will move around a common centre of gravity
• take a spectrum and create a light curve vs velocity
• biased to hot Jupiter’s (large and close)

Question 23

Advantages and disadvantages of Doppler shifts

Answer 23

•Advantages:
      -false detections unlikely
      - orbits do not need to be edge on
      - very successful
•Disadvantages:
      -uncertainty in inclination angle of mass
      - bias towards high mass and close 
      - requires larger telescopes

Question 24

Transits

Answer 24

• measuring brightness of orbit as function of time
• have repeated transits to know something is orbiting
• light curves provide a measurement of radius and other parameters

Question 25

Advantages and disadvantages of transits

Answer 25

•Advantages:
      -see many stars 
      - smaller telescopes
      - radius and possibly atmosphere determined
•Disadvantages:
      - system needs to be edge on
      - lots of false alarms
      - needs Spectroscopic confirmation

Question 26

Direct imaging

Answer 26

• taking a photo of the exoplanet

- very hard due to how bright stars are

Question 27

Advantages and disadvantages of Direct imaging

Answer 27

•Advantages:
      -see pictures of exoplanets
•Disadvantages:
      - very hard observationally
      - must prove it’s a planet
      - braised towards high mass/ large separation

Question 28

Habital zone

Answer 28

• is the place where liquid water can form
• closer to low mass stars and farther from high mass stars for right temperature
• Kepler is making a big difference in tally of Earth sized planets
• 17% stars in Milky Way host an Earth sized planet - 17 million Earths