Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

Astrobiology: Exploring Other Worlds > Week 1: Planets in the Solar System and Beyond > Flashcards

Week 1: Planets in the Solar System and Beyond Flashcards

1
Q

What is the Copernican Principle?

A

Humans and Earth don’t hold a special place in the universe - we are fairly average and normal.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

What defines a planet?

A
  1. orbiting around a sun
  2. large enough to have enough gravity to become round and clear its surrounding neighborhood
  3. too small to generate nuclear energy (significantly smaller than a star)
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

What was surprising about 51 Pegasi b when it was discovered?

A

01 first exoplanet orbiting a star discovered
02 really short orbit (4.4 days)
03 closer to its star than was previously thought possible

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

What’s notable about the Kepler satellite in relation to exoplanets?

A

01 responsible for a majority of later exoplanet discoveries (2009 and onwards)
02 allowed us to detect smaller exoplanets more similar to earth (not like the gas giant of 51 Pegasi b)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

What is the Doppler technique?

A

a method of discovering exoplanets
look at the subtle gravitational effects of exoplanets on their parent stars

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

What is the Kepler method?

A

a method of discovering exoplanets
look at a star’s brightness to detect subtle dips, indicating a planet moving in front of the star periodically

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

What is eccentricity? (include actual numbers)

A

a measure of how much a planet’s orbit differs from a perfect circle
e=0 indicates a perfect circle orbit
e=1 highly eliptical

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

How does the eccentricity of planets in our solar system compare to the eccentricity of exoplanets?

A

Planets in the solar system have generally not very eccentric orbits, while exoplanets can get a lot more eccentric.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

How does eccentricity contradict the Copernican principle?

A

planets in the solar system are so much less eccentric than lots of the exoplanets we have discovered so maybe we are special after all

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

What do stars form out of, and what are its properties?

A

molecular clouds
very dense and dusty gaseous clouds of atoms that are so cold that they stick together and become molecules such as H2, CO2, CH4

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

How is planet formation related to star formation?

A

It happens at the same time! As a star forms, planets form around it.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

What starts star formation?

A

collapsing of a molecular cloud
can be motivated by a nearby supernova

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

What is the protoplanetary disc?

A

area of molecular cloud around a star that is left over from star formation
where planets eventually form

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

What happens to material in the protoplanetary disc not used up by planet formation?

A

driven away by the parent star’s radiation

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

What is the frost line? What can be found on either side of it?

A

the minimum distance from a star at which hydrogen compounds can form ice
inside of frost line is where rocky + metallic materials are (rocky planets)
outside of frost line is more icy/watery rocks (gas giants)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

What is differentiation for rocky planets?

A

the process by which molten material in newly formed rocky planets separates itself into layers based on density
denser elements sink down to planet’s core
creates solid crust, molten mantle, and solid core like earth

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

How does differentiation happen in gas giants?

A

molten material separates itself into layers based on density
forms core of heavy molten materials (vs rocky planets’ solid core)
atmospheric layers - outer layer of cold gas, inner layer of super heavy pressure means matter exists simultaneously as solid, liquid, and gas

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

How many stars are in the milky way?

A

100-400 billion stars

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

What kind of star is most common in the milky way?

A

long-lived small red dwarfs (difficult for us to observe)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

How many stars are estimated to have planets?

A

As few as 20% or as many as 90%

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

Describe the mass breakdown of a solar system (What percent of mass is certain materials?)

A

less than 1% metals + rocks
1.4% hydrogen compounds (H2O, CH4, NH3)
98% hydrogen + helium gases

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

What is the condensation curve?

A

describes what materials can be solid/liquid based on their distance from the host star
metals and rocks condense at high temperatures, so they exist close to the host star
hydrogen compounds condense at the second highest temperatures (exist further from star than rocks/metals)
gases condense at the lowest temperatures so they are most common the furthest from the host star
Vaporization temperature of a material is the closest it can get to its host star (when a material is vaporized, radiation pushes it away)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
23
Q

What is radiation pressure and what does it do?

A

pressure from stars that drives away gas and dust from the star’s immediate vicinity (leaves rocks and metals)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
24
Q

What are the characteristics of small rocky planets?

A

aren’t big enough to have atmospheres (not enough gravity)
don’t generally have geological activity
cratered surface - no atmosphere to protect from space objects

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
25
Q

What are the characteristics of large rocky planets?

A

can have substantial atmospheres
constantly shifting surfaces (geological activity)
molten core caused by differentiation -> magnetic field, which helps retain atmosphere and protect surface from solar radiation

26
Q

What does it mean when a planet is tidally locked?

A

One side of the planet always faces its host star as it orbits
happens when a planet is very close to its star

27
Q

What are the characteristics of gas giants?

A

large planets outside the frost line made up of hydrogen + helium gas + frozen hydrogen compounds (ices)
strong gravity due to large side causes gas layers to compress -> internal heat which increases as you move closer to the center, also causes differentiation

28
Q

What happens to gases in the lower levels of a gas giant’s atmosphere?

A

exist as supercritical fluids (between a liquid and gas, sometimes also properties of solids)
caused by high pressure

29
Q

What are the three ways moons can form around a planet?

A

01 leftover material from planet formation creates mini debris disc (similar to planet formation)
02 collisions
03 planetesimals being pulled into orbit

30
Q

True or false: Humans have discovered exomoons.

A

False - we haven’t yet but we assume they exist due to the high presence of moons in our solar system

31
Q

What characteristics similar to planets can moons have?

A

atmospheres, geological activity, heat sources (from tidal effects or radioactive cores)

32
Q

What is a terrestrial planet and how many are in our solar system?

A

same as a rocky planet (solid surface planet made up of mostly rocks and metals close to host star)
we have 4 in our solar system

33
Q

What is a Jovian planet and how many are in our solar system?

A

same as gas giant (large gaseous planet made up mostly of hydrogen compounds and gases)
we have 4 in our solar system

34
Q

What are the characteristics of Mercury (the planet)?

A

geologically dead
no atmosphere

35
Q

What are the characteristics of Venus?

A

similar to earth geologically
very high surface temperature (900F) and pressure (100atm)
similar amount of CO2 to earth but concentrated in atmosphere and not oceans (causes runaway greenhouse effect)
could have been habitable 3 billion years ago! (liquid water, no runaway greenhouse effect)

36
Q

What is the runaway greenhouse effect?

A

CO2 in atmosphere traps heat on a planet, which increases volcanic activity and increases CO2 in atmosphere (positive feedback loop)

37
Q

What are the characteristics of Mars?

A

smaller than Earth
less geologically active than Earth
may be water, but is concentrated underground
could have been more habitable 3 billion years ago (liquid water, higher temperatures, thicker atmosphere)

38
Q

What are the characteristics of Jupiter and Saturn?

A

together make up 71% of planetary mass in solar system
so big that their gravity impacts other parts of solar system
very low density (saturn would float in water)
surrounded by icy rings

39
Q

What are the characteristics of Uranus?

A

ice giant (smaller + icier gas giant)
rotates on its side - seasons are centuries long (something probably ran into it)

40
Q

What are the characteristics of Neptune?

A

ice giant (smaller + icier gas giant)
blue due to methane in atmosphere
very offset magnetic field
highest wind speeds in universe

41
Q

What is the Kuiper belt?

A

region of rocky debris in outer solar system
probably where Pluto was captured from
contains some objects equal size / larger than Pluto

42
Q

What is a hot jupiter?

A

a gas giant as big as or bigger than Jupiter than is very close to its parent star
surface temp >= 1000K
orbital period <10 days
-> 51 Pegasi b
supports theory of planet migration

43
Q

What is planet migration?

A

the idea that planets move after being formed and may not necessarily have formed in the area they are observed today
planets interact with other matter and spiral inwards towards host star before settling into final orbit
becomes tidally locked and stops migrating further

44
Q

What is the grand tack theory?

A

theory that suggests that early Jupiter underwent planet migration
01 gravity of planetesimals impacted early gas giant
02 jupiter and saturn crossed an orbital resonance -> orbits become more eccentric, Uranus and Neptune also affected
03 uranus and neptune clear away planetesimals and send some inwards (great bombardment)

45
Q

What is orbital resonance?

A

When two planet’s orbits are related with a small whole number ratio
have a regular gravitational impact on each other as their orbits regularly align

46
Q

What is the great bombardment?

A

hypothesized event on early solar system in which uranus and neptune clear away planetesimals from their orbits and send them inwards
seen in crater history of inner planets

47
Q

True or False: we can be relatively confident in the accuracy of models of planet migration.

A

False - planet migration is very chaotic!!

48
Q

True or False: our solar system is full.

A

True - if another planet were added to our solar system, it would likely become unstable

49
Q

What is the chemical makeup of ice giants compared to gas giants?

A

much more heavier elements/compounds with higher freezing points (oxygen, carbon, nitrogen, sulfur)
only 20% hydrogen/helium vs gas giants’ 90%
still have lighter elements in outer atmosphere, but become heavier closer to core

50
Q

What is the state of matter makeup of ice giants?

A

30% solid ice
70% supercritical fluids

51
Q

What defines an earthlike exoplanet? What are the two categories of earthlike exoplanets?

A

mass of <= 10 earth masses
mini neptunes and super earths

52
Q

What is a mini neptune?

A

also known as gas dwarf
similar composition to ice giants uranus/neptune but smaller
dense hydrogen/helium atmosphere
similar surfaces to ice giants (liquid oceans due to high atmospheric pressure, small rocky/icy core)
large orbital distance
very low temperatures

53
Q

What is a super earth?

A

rocky planets similar to earth in composition but bigger
can be low to high density (more similar to gas dwarfs to very rocky + metallic)
probably have a bunch of geologic activity
- larger than earth -> more pressure on thin outer crust -> more geologic activity -> indicator of potential life???

54
Q

How is the search for earth-like planets going right now?

A

we’ve found a lot, but no direct earth twins

55
Q

What does the distribution of the masses of discovered exoplanets show?

A

most planets discovered are right up against the minimum size we can detect at the moment
there are lots of planets we can’t find yet!!

56
Q

Roughly how many exoplanets have been discovered + confirmed?

A

5,500

57
Q

What is the type makeup of all the discovered exoplanets?

A

most common - ice giants
somewhat common - hot jupiters
roughly a quarter super earths

58
Q

What is the Kepler mission?

A

1 meter space telescope that observed a small fraction of the sky for 5 years
discovered 2,600+ exoplanets

59
Q

What is the K2 mission?

A

observed specific sky area looking at a new area every 80 days for 3 years
discovered 300 exoplanets

60
Q

What is the WFIRST telescope?

A

notable for wide-field of vision -> potentially could find lots of exoplanets
will launch in 2027

61
Q

What is the TESS satellite?

A

mission to complement Kepler
looks at a larger area of sky to focus on more nearby planets with brighter stars

Astrobiology: Exploring Other Worlds (6 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions