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PHYS 183 > Lecture 6 - Solar System Formation > Flashcards

Lecture 6 - Solar System Formation Flashcards

1
Q

what type of elements make up most of the atmosphere? where did they come from?

A

light elements like He make up most of the atmosphere –> involved in Big Bang

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2
Q

do heavier elements come from the big bang?

A

no, but they are very important now

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3
Q

what are the 4 main features of the solar system that must be explained by a theory of solar system formation?

A
  1. Patterns of motion –> all orbit in same direction+ motion
  2. Terrestrial and jovian planets
  3. Asteroids and comets and why they have specific places they reside
  4. Notable exceptions
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4
Q

what are 3 places where asteroids and comets reside?

A
  1. asteroid belt
  2. kuiper belt
  3. Oort cloud
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5
Q

what are 2 notable exceptions to the patterns of the solar system?

A
  1. rotation of Uranus
  2. Earth’s moon
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6
Q

what does the Nebula Theory state?

A

states that our solar system formed from gravitational collapse of a giant interstellar gas cloud (SOLAR NEBULA)

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7
Q

what does nebula mean in latin?

A

Nebula = cloud

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8
Q

what does the close encounter theory state?

what does this theory NOT explain? (2)

what type of event would this theory require?

A

states that planets formed from debris torn off the Sun by a close encounter with another star

doesn’t explain orbital motions or 2 types of planets

would require a highly probable event –> very small chance of a star colliding with the sun and cannot account for other types of planetary systems

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9
Q

is the nebular or close encounter theory more probable?

A

nebular

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10
Q

what is galactic recycling?

A

the Big Bang only produced H and He and heavier elements were produced from the death of massive stars and mixed with interstellar gas to form new stars

i.e. stars produce heavier elements from lighter ones

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11
Q

describe the series of events in the nebular theory

A
  1. solar nebula started as large, spherical cloud of cold, low-density gas
  2. cataclysmic event triggered the collapse of the cloud
  3. strength of gravity increased as the cloud got smaller which made the diameter cloud get even smaller and smaller
  4. cloud became a disk
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12
Q

what could have been the cataclysmic event triggering the collapse of the solar nebula?

A

impact of a shock wave from the explosion of a nearby star (SUPERNOVA)

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13
Q

what type of physics allows the collapse of the cloud? explain this

A

ANGULAR MOMENTUM

as the cloud got smaller, it rotated faster (like spinning figure skater) and pulled in more gas and matter as it sped up
- the rapid rotation prevented total collapse into the center so there was INCREASING ANGULAR MOMENTUM and spread out into a DISK

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14
Q

explain why the cloud collapses into a disk

A

cloud starts off with different clumps of gas moving in random directions at random speeds

the clumps collide and merge as the cloud collapses and each new clump gets the average velocity of the clumps that formed it so the motion becomes MORE ORDERLY and speeds up a lot to cause increased angular momentum that can spread out into a disk

^the collisions reduce up and down motions

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15
Q

what happens when dark matter collapses? why?

A

forms a sphere because there are no interactions, so there are many up and down motions

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16
Q

what can we see in the solar system that may confirm the nebular theory? how?

A

we see nebular disks forming elsewhere

there is a spiral pattern indication the presence of 1+ Jovian planets forming in the disk and gaps indicate forming planets

17
Q

why are simulations helpful?

A
  1. helps with intuition bc we cant see or calculate everything
  2. can map theoretical observations using the laws of physics
  3. can compare and confirm with actual images
18
Q

describe what happens inside and outside frost line. what is the difference?

A

INSIDE FROST LINE: too hot for H compounds to form ices so metal and rock condense into solids

OUTSIDE FROST LINE: cold enough for metal and rock ices to form

accumulation and condensation of dust is different on either side of frostline

19
Q

describe the formation of terrestrial planets

why are they small?

what happens to gas?

A
  1. planetesimals of metal and rock built from small particles of metal and rock inside the frost line as they collide
  2. gravity assembled the planetesimals into terrestrial planets (ACCRETION)

small bc metal and rock only make up a small amount of material in the solar nebular

gases leave and diffuse out

20
Q

what is accretion?

A

many smaller objects collide to form a few large ones

21
Q

why was accretion different for jovian planets compared to terrestrial planets?

A

Jovian planets have more condensation of ices

therefore:
1. there was more solid material
2. the solid material contained ice in addition to metal and rock

22
Q

describe the formation of jovian planets with regards to:
1. size
2. effect of gravity
3. moons
4. what happens to gas

A
  1. ice allows for larger planetesimals and planets
  2. gravity draws in surrounding H and He
  3. spinning disks around the planet forms large moons by condensation and accretion, then captures small moons
  4. photons and solar wind blow away leftover gases
23
Q

how has the rotation of the sun changed over time? why?

A

the sun rotates much slower now

bc of friction btwn solar magnetic field and solar nebular

24
Q

what have the leftovers from planet formation/accretion formed?

A

the leftovers from planet formation/accretion formed asteroids and comets

25
Q

what are asteroids?

A

rocky, leftover planetesimals of inner solar system

26
Q

what are comets? why do they have tails?

A

icy, leftover planetesimals of outer solar system

have elliptical movements so when they get close to the sun, ice is blown off the back and produces a tail

27
Q

describe the heavy bombardment of asteroids and comets

A

during the late stages of solar system formation, leftover planetesimals bombarded other object

28
Q

why are many asteroids and comets gone now?

A
  1. were flung into deep space by gravitational encounters
  2. collided with planets
29
Q

where could Earth’s water and H compounds have come from?

A

brought to Earth by icy planetesimals

30
Q

what does the nebular theory account for? (4)

what are exceptions likely caused by?

A

accounts for:
1. terrestrial planets
2. Jovian planets
3. comets
4. asteroids

exceptions likely caused by large collisions or close gravitational encounters

31
Q

where do unusual moons likely come from? how do they form for Jovian planets?

A

unusual moons are likely captured planetesimals

for Jovian planets: passing planetesimals must have lost energy to friction in the dense gas that surrounded the planets as they formed –> reducing the orbital energy of the planetesimals and allowing them to switch from an unbound orbit to a bound orbit

32
Q

what is a characteristic of a spherical moon?

what is a characteristic of a non-spherical moon?

A

SPHERICAL MOON –> lots of frosted water

NON-SPHERICAL MOON –> impacted by comets

33
Q

why do we believe Earth’s moon was not captured?

A

too large!! could not have formed simultaneously because would have accreted from planetesimals of the same type and would have same composition and density

moon has lower density and diff composition than Earth

34
Q

how do we believe we got the moon?

A

GIANT IMPACT

Earth-like planet crashed into Mars-sized planetesimal and they shattered

  • Earth became molten and rapidly rotated to increase its spin
  • some debris joined the planetesimal and formed the moon
35
Q

what could explain odd rotation of certain planets?

A

due to giant impacts

36
Q

what are the 3 exceptions to the rules of the nebular theory?

A
  1. captured moons
  2. our moon
  3. odd rotation
37
Q

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

A

frostline would be closer to the sun so outer terrestrial planets would be Jovian instead

38
Q

is the number of planets of each type explained by the nebular theory?

A

no

PHYS 183 (20 decks)

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