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Astro 103 > Astro Exam 2 (5/8/23) > Flashcards

Astro Exam 2 (5/8/23) Flashcards

1
Q

motion of the planets

A

all planets in the solar system orbit in the same direction (counterclockwise) and nearly the same plane
- pluto’s orbit is not the same plane as the major planets

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2
Q

rotations

A

most planets rotate in a counterclockwise direction
- Venus rotates in the opposite direction - clockwise

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3
Q

tilts

A

venus and mercury have a tilt of almost 180° compared to other planets - perpendicular
Uranus - 90°

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4
Q

terrestrial planets

A

inner planets:
- rock and metal, density is roughly the same
- mercury, venus, earth and mars

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5
Q

jovian planets

A

outer planets:
- much larger in scale, made up of gas
- Jupiter, Saturn, Uranus, Neptune

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6
Q

asteroids

A

asteroid belt - rocky band btw mars and jupiter
kuiper belt - beyond neptune’s orbit
oort cloud - edge of solar system

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7
Q

meteor

A

hard to predict, very random
meteor showers - happen on the same days every year

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8
Q

comets

A

Halley’s comet comes around every 76 years

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9
Q

close encounter hypothesis

A

the planets formed from debris torn off from the sun by a close encounter with another star - but this doesn’t explain motions, types of planets and why the giant planets are further from the sun

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10
Q

solar nebula theory: basic description

A

our solar system formed from the gravitational collapse of a giant interstellar gas cloud - the “solar nebula”
- start with a rotating cloud of gas
- contracts and flattens to become a thin disk of cloud and dust forming the sun at the center
- planets grow from gas and dust in the disk are left behind when the disk clear

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11
Q

solar nebula theory: frost line

A

energy from the baby star that is forming warms up the surrounding area that is too hot from anything but rock and metal and outside the frost line its cool enough for the outer planets

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12
Q

solar nebula theory: terrestrial -planetesimals

A

rock and metals that grew as the particles collided

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13
Q

solar nebula theory: terrestiral- accretion

A

gravity eventually assembled these planetesimals into the terrestrial planets

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14
Q

solar nebula theory: terrestiral - protoplanets

A

starts as uniform metals and rocks that gather together in a big ball but some are radioactive and heat up the inside of the planet and denser metals sink to the center = differentiation

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15
Q

solar nebula theory: jovian planets

A

large icy planetesimals and protoplanets formed and the gravity of the large protoplanets was able to draw in surrounding hydrogen and helium gas resulting in large planets

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16
Q

solar nebula theory: asteroids/comets

A

leftover pieces from the assertion process, inside the frost line = asteroids, outside the frost line = comets

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17
Q

solar nebula theory: asteroid belt

A

protoplanets between mars and jupiter were forced apart by jupiter’s gravity

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18
Q

solar nebula theory: moons

A

leftover planetesimals bombarded other objects in the late stages of solar system formation creating craters
earth’s moon:
- collision theory: grazed the earth and the metallic center of both objects made earth’s core denser and the rocky material flung out into space and became the moon

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19
Q

conservation of angular momentum

A

rotation speed of the cloud from which our solar system was formed must have increased as the cloud contracted
rotation of contracting cloud speeds up as it gets smaller

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20
Q

disk flattening

A

collisions between gas particles in a cloud gradually reduce random motion - “up and down” vertical motions are reduced and they flatten into a disk shape as it shrinks

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21
Q

Ussher: age of the earth

A

calculated the age of the earth by working backward through the bible and comparing it to known historically events
according to him the earth was created at 6pm on Sat, October 2, 4004 BCE

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22
Q

pierre and marie curie

A

discovered radioactivity
radioactive dating gives an age of rocks on the earth of about 4 billion years
moon rocks and meteorites can be similarly dated using radioactive isotopes = age of the earth is 4.6 billion years

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23
Q

radioactive decay

A

C₁₃ is unstable and overtime decays
half-life - a measure of how quickly an isotope will decay
after each and every half-life, the number of remaining radioactive nuclei is reduced by a factor of two

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24
Q

cooling of planetary interiors - energy transport

A

Conduction - transfers heat from hot material to cool material
Convection - transports heat as hot material rises and cool material falls
Radiation - sends energy into space in the form of light

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25
Q

planetary magnetic fields

A

molten, electrically conducing interior
convection
“moderately rapid motion”

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26
Q

processes that shape surfaces

A

impact cratering - asteroids or comets
volcanism - eruption of molten rock onto surface
tectonics - disruption of a planet’s surface by internal stresses (convection)
erosion - surface changes made by wind, water or ice

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27
Q

moon

A

lava part of the moon has fewer craters because its younger than the cratered highland part created during the heavy bombardment period

28
Q

Mercury: surface

A

surface of mercury looks like Earth’s moon a little bigger than the moon
“Caloris Basin” - large collision on one side of Mercury
“Weird terrain” - created by the collision that made the Caloris Basin that pushed the surface of Mercury to form wrinkles
Small planets are affected the most by impact cratering because they have little atmosphere and no volcanism

29
Q

Mercury: days

A

Sidereal day (one rotation) - 59 Earth days
Solar day - 176 earth days
Mercurial year - 88 earth days

30
Q

Mercury: magnetic field and tilt

A

Metallic core, convection, “moderate” rotation is slow - weak magnetic field
Mercury doesn’t have seasons because it has a very small tilt

31
Q

Venus: surface

A

Covered in clouds
A little smaller than the Earth and similar surface gravity
Looks so bright in our sky because the white clouds reflect a majority of the sunlight
Very similar geological features as the earth
Volcanoes - more than any planets, ~85,000 some are still active
The most mountainous parts of Venus have no volcanoes
The “miss piggy” Corona - in the plains to the south of Aphrodite Terra
Pancake domes - wider than they are high, created by very thick lava that bubbles out onto the surface

32
Q

Venus: days

A

Sidereal day - 243 earth days
Solar day - 117 earth days
Venusian year - 225 earth days

33
Q

Venus: magnetic field and tilt

A

Doesn’t have a magnetic field and no seasons because tilt is almost 180 degrees
Hotter than Mercury despite being farther from the sun - due to thick atmosphere
Tilt from ecliptic - 177 degrees

34
Q

Mars: surface

A

Mostly rock than metal
Halt the size of the earth and 40% of the earth’s gravity

35
Q

Mars: tilt and magnetic field

A

Tilt of 25.2 degrees with similar seasons as the earth
Morning fog - water vapor
Dried-up river deltas, used to be covered in water
Melted salt water
No magnetic field because its core is very small, and cooled off much farther than the Earth so there is no convection

36
Q

Mars: days

A

Sidereal and solar day - 24.6 hours, 1 “sol”
Martian year - 1.88 earth days

37
Q

Moons of Mars

A

Phobos and Deimos
Very small, and oddly shaped because they are too small
Phobos: slowly spiraling towards Mars due to tidal forces an will crash in 50 million years
Deimos: slowly spiraling away from Mars

38
Q

law of conservation of energy

A

energy in = energy out

39
Q

inverse square law of light

A

intensity of light increases as proximity to the light source decreases

I = P/4πr²

I = intensity
P = power of light

40
Q

earth’s atmosphere: light rays

A

x-rays and UV rays get absorbed before reaching the surface of the Earth
visible and infrared light reaches the earth unimpeded

41
Q

earth’s atmosphere: troposphere

A
  • lowest layer
  • temp drops with altitude
  • warmed by infrared light from the surface and convection
  • where weather occurs
  • commercial airplanes fly
  • temp decreases with higher altitude because the density of the air is lower
42
Q

earth’s atmosphere: troposphere - greenhouse effect

A

visible light comes in –> some is reflected by clouds and the surface –> infrared light bounces and stays trapped int he layers of the atmosphere

43
Q

earth’s atmosphere: sky color

A

the sky is blue because the bluelight from the sun is scattered around the atmosphere
scatter effect: based on the length of the colors so the longer wavelengths (red, orange, yellow and green) reach the earth but the blue and violet ones bounce around

44
Q

earth’s atmosphere: stratosphere

A
  • ozone layer
  • temp rises with altitude
  • warmed by absorption of UV sunlight
45
Q

earth’s atmosphere: mesosphere

A
  • heated by UV light but the temp decreases with altitude
  • meteors typically burn up in this layer
46
Q

earth’s atmosphere: thermosphere and exosphere

A
  • highest layers in which atmosphere gradually fades into space
  • space begins are 100 km above sea level = Von Kármán line
  • temp rises with altitude so fast-moving atoms can escape into space
  • atmosphere is heated and protially ionized by x-rays and UV light
47
Q

earth’s atmosphere: magnetic field

A
  • extends out beyond the atmosphere
  • deflects the path of charged particles
  • protects from solar wind
  • gaps in the magnetic field cause the solar particles to spiarl in and get drawn towards magnetic north and south = northern/southern lights
48
Q

creating an atmosphere

A
  • mostly nitrogen, 1/5 oxygen, very little argon, water, and CO₂
  • outgassing: water, carbon dioxide, nitrogen and sulfur compounds
    i) associated with volcanoes but planets can still have outgassing without volcanoes
    ii) as the planet cools off it releases all the vapor that was originally in the solar nebula
  • evaporation - surface liquids or ices
  • ejection from impacts
49
Q

decreasing an atmosphere

A
  • condensation
  • chemical reactions
  • solar wind: nonreversible
  • thermal escape: nonreversible
  • high temp
50
Q

decreasing an atmosphere: thermal escape

A

thermal escape: nonreversible
i) gravity of a planet determines how tightly the planet can hold onto its atmosphere
ii) escape velocity is the speed at which you throw something up and it won’t come back (earth =11.2 km/s)
iii) the higher the mass the stronger the gravity and the harder it is for the atmosphere to escape

51
Q

mercurial atmosphere

A

doesn’t have much of one because the escape velocity is high, has a weak magnetic field so its not well protected from the solar wind

52
Q

Venusian atmosphere (90 bar): basic description

A

has an atmosphere because despite it having super high temp, its mass is big enough to hold onto its atmosphere

53
Q

Venusian atmosphere (90 bar): composition

A

based on the light spectrum we can tell what elements are in it
- mostly CO₂, little nitrogen, very little oxygen and water

54
Q

Venusian atmosphere (90 bar): layers

A
  • sulfuric acid cloud layers: rains sulfuric acid on Venus but its so hot that it never reaches the surface
  • troposphere: 100km vs Earth’s 10km
  • no ozone layer because there isn’t enough oxygen on Venus
    i) if CO₂ contained in the Earth’s crust were somehow released our atmosphere would become 98% CO₂ and pressure would increase by a factor of 70
55
Q

Martian atmosphere (0.006 bar): composition

A
  • mostly CO₂, some nitrogen and argon, very little oxygen and water
  • much thinner compared to Earth or Venus because it has less gravity
  • too thin to retain the heat so the surface temp drops sharply at night
56
Q

Martian atmosphere (0.006 bar): layers

A

very little magnetic field because its smaller than earth and cooled off faster - not molten and its contains less iron
- North Polar Cap: dry ice, freezes at a lower temp than water

57
Q

radioactive decay

A

major source of energy now

58
Q

atmospheric convection

A

when the ground is warmed by the sun causing the air above the hot ground which is less dense than cool air so it rises making a vacuum

59
Q

planetary sizes

A
  • smaller worlds cool off faster and solidify quickly
  • larger worlds remains warm inside, promoting volcanism and tectonics
  • larger worlds also have more erosion because their higher gravity can retain an atmosphere
60
Q

surface area-to-volume ratio

A
  • volume = 4/3πr³
  • surface area = 4πr²
  • cooling time: volume/ surf. area = r/3
    therefore larger radius planets cool more slowly
61
Q

surface area-to-volume ratio

A
  • volume = 4/3πr³
  • surface area = 4πr²
  • cooling time: volume/ surf. area = r/3
    therefore larger radius planets cool more slowly
62
Q

interior structure of earth

A
  • crust: lowest density, granite, basalt etc
  • mantle: moderate density, silicon, oxygen etc
  • inner: highest density, nickel and iron
  • outer cores: liquid metals
  • not all of the center of the earth is liquid because of the pressure
  • we know about the inside of the earth because of earthquakes
63
Q

types of waves

A
  • pressure “P” waves: compress and stretch matter, changing the density of the material
    i) passes through liquids
  • shear “S” waves: shake matter side to side, material vibrates from side to side
    i) doesn’t travel through gasses or liquids
  • the speeds of both types of waves depends on the properties of the matter that transmit them
64
Q

earthquakes and waves

A

by analyzing the kind of waves from earthquakes geologists can detect what is inside the core of the earth

65
Q

tidal lock

A

earth’s gravity stretches the moon causing the long axis of the moon to always face us
perigee - when the moon is closer to the earth
apogee - when the moon is farther away from the earth

66
Q

formation of lunar Maria

A

1) early surface is covered with craters
2) large impact crater weakens crust
3) heat build-up allows lava to well up to surface
4) cooled lava is smoother and darker than the surroundings

67
Q

interior structure of the moon

A

very small liquid part in the center

Astro 103 (3 decks)

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