Exam 1 Study Guide
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EAPS 105, The Planets
Exam 1 Study Guide
Know the following:
Unit 1: Solar System Origins
1. The percent of the Solar System’s mass contained in the Sun.
99.86%
2. The percent of the mass of our Solar System’s planets contained in Jupiter.
70%
3. What is an astronomical unit (AU).
distance from the Earth to the Sun
4. The distance from the Sun that Jupiter is compared to Earth (in AU).
Jupiter is about 5 AU from the Sun
5. Whether the distance from the Earth to the Moon is changing.
Yes moving away
6. What most of the objects that you can see in the night sky with your naked eye are.
stars in our galaxy
7. Where the first helium atoms originated from.
high temperature and pressure caused hydrogen ions fuse into helium
8. Why fusion produces heat.
mass is converted to energy (E=mc^2)
9. The difference between hydrogen ions and molecular hydrogen.
molecular hydrogen doesn’t glow, so the universe appears dark (cooled hydrogen ions become molecular hydrogen)
10. Why nuclear fusion produces heat and light.
11. What the James Webb telescope focused on to create the Deep Field image.
the darkest patch of the sky
12. The elements fused within a low-mass star like the Sun. Hydrogen fuses into helium, then beryllium, then carbon, then oxygen
13. The two forces that maintain balance within a star.
gravity contracting and fusion in the core creates an outer pressure pushing out
14. The fate of the core within a low-mass star like our Sun when fusion begins to shut down.
( low mass star heats up as the core contract, and the heat causes the outer regions to expand and cool, causing the star's light to shift to redder part of the spectrum)
red giant> white dwarf> planetary nebula(outgassing the outer layers)
15. The fate of the outer regions of a low-mass star when fusion begins to shut down.
the expansion of the outer regions cause them to disperse into space(outgassing), called planetary nebula. They are relatively small gas clouds of ionized hydrogen that glows.
16. Why the emitted light of dying stars is redder.
see problem 14
17. What planetary nebulae are.
A nebula consisting of an expanding, glowing shell of ionized gas ejected from red giant stars late in their lives.
18. The fate of our Sun.
It will become a white dwarf (core) and planetary nebula (outer region).
19. The fate of the largest stars.
Cores condense into black hole and outer regions explode as supernova.
(large star> red supergiant> black hole+ supernova)
20. How mass effects the longevity of stars.
1
larger mass last shorter( they are hotter)
21. Characteristic of a red dwarf stars.
They are the smallest stars. They are low mass and coolest, thus having a redder appearance. Because they burn very slowly, they can live for a trillion years.
22. The heaviest element that can be fused in the core of a high mass star.
ion
23. Why supernovas occur.
When fusion ceases in a massive star, the core collapses extremely fast causing shock wave of a high pressure that causes the outer part of the start to explode. This is called supernova.
form new stars( spread elements that become components of new solar systems) from the remnants
24. What supernovas do that fusion in the cores of stars cannot.
fusion of elements heavier than iron that cannot otherwise be fused within stars. (supernova higher temperature than core)
25. The processes that can generate a supernova.
1. explode(as in prob 23)
2. white dwarf accretes material from a companion star causing it to gravitationally compress, heat up and explode
3. collision of two neutron stars causes the largest type of supernovas that leads to the heaviest elements (often lead to blackhole)
26. Why low mass stars have heavy elements.
inherit from previous supernovas (quiz)
27. Where the atoms in your body come from (generally, not specifically).
remnants of stars and hydrogen is from the big bang
28. The correct sequence of the Solar Nebula Hypothesis (start anywhere in the cycle)
diffuse cloud > dense cloud> accretion disk> stellar system> mass loss
29. The source of material in current nebula.
supernova remnants
(nebulas are large clouds of gas and dust)
30. Where stars are born.
clumps within molecular clouds contract to initiate the fusion of hydrogen into helium, giving off light and heat
31. The type of nebula comprised of hot hydrogen ions (H+) that glow.
emission nebula ( as they cool, hydrogen ions form into molecular hydrogen and they do not emit light, but reflect it)
32. How the force of gravity between two objects is affected by their distance.
greater gravitational force for smaller distance and bigger mass.
33. Why nebula clumps contract.
gravity
34. How concentrating the mass of a rotating object influences its rotation rate.
conservation of angular momentum L=m*r*w
35. What an accretionary disc is.
new stars end up surrounding by a spinning disk of gas and dust called accretionary disc.
(conservation of angular momentum cause denser clumps within nebula to spin faster> spinning becomes rapid that many new stars flung out of the nebula)
36. Why already spinning nebula clumps flatten into accretionary discs.
collisions between gas and dust molecules that serve to cancel up and down motions relative to the spin axis.
Unit 2: Planet Formation
37. What meteoroids are.
2
small rocks ( les than a few meters across) traveling through space
38. What meteors are.
small rocks from space that light up in the night sky as they burn up Earth's atmosphere
39. What meteorites are.
small pieces of space rock that survives and hit the Earth.
40. Why a fusion crust forms on a meteorite.
caused by melting when a meteor passes through the atmosphere.
41. The easiest place to find meteorites.
Antarctica. The flowing glaciers collect and deposit them, and winds erode the ice above to expose them.
42. How farmers often find meteorites.
buried in field where nothing can grow due to contamination of nickel.
43. Where most meteorites come from.
most meteorites are fragments of asteroids( chunks of space rock leftover from the formation of the planets from the original accretionary disc). some come from moon and mars
44. What chondrules are.
melted balls of dust clumps from the very beginning of the solar system
(formation: clumps of dust are flash heated into small balls of melted rocks and metal)
45. The basic characteristics of chondritic
meteorites.
the rocks have not been altered( the oldest unmodified rocks in solar system), show that the parent asteroid was a collection of chondrules.
46. The basic characteristics of achondritic
meteorites.
do not have chondritic because they have been melted by high temperature which cause them
to mix with other minerals. (the age of rock is denoted by the last time it was altered)
47. The story of the Lafayette Meteorite.
it has gas inclusions that match the atmospheric element of Mars
(1. from a 1.3 billion-year-old lava flow 2. 670 million years ago it was exposed to salty water 3. 11 million years ago it was ejected from the surface of Mars by an asteroid impact)
48. The steps of accretion from dust to planets.
dust> chondrules> planetesimals> protoplanets> planets
49. The force that enables dust particles to accrete to each other.
electrostatic attraction (stronger than gravity for this small scale)
50. What it means for an asteroid or planet to be differentiated.
internal structure is stratified with different layers with increasing density with depth. (collision and radioactive elements produce heat)
(undifferentiation> internal heating> melted interior>differentiated)
(chondritic meteorites come from the breakup of small undifferentiated asteroids, achondritic
meteorites come from much larger differentiated asteroids)
51. How an asteroid or planet obtains an iron core.
melting of interiors of large bodies enable denser elements like iron to sink ( iron itself is inherited from big bang)
52. The prevalence of terrestrial planets to have iron core.
accretion, internal heating, then differentiation led the four terrestrial planets to each have an iron core and a rocky mantle and crust.
53. Why the Moon’s core is proportionally small.
very different because it formed in different fashion: a giant impact(moon) as opposed to accretion (earth)
54. Why Mercury’s core bise so proportionally big.
1. a giant impact blew off most of its mantle
2. its outer layers were vaporized by a hot young Sun
3. it was assembled from mostly metal-rich building blocks and thus never had a large mantle
3
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55. How the chemistry of the Sun is determined.
when sunlight passes thru gas, the elements present in that gas absorb certain frequencies of light. The resulting absorption spectrum show the elements are present in the sun's atmosphere
56. Aside from hydrogen and helium, the most abundant element in our Sun.
oxygen
57. The type of elements that condense from a gas to a solid at relatively low temperatures.
volatiles (refractories: at high temp)
58. Where the ice line is currently located.
just inside Jupiter's orbit ( the location where temperatures are cool enough for solid ices)
59. The important of ice in the development of the giant planets.
The giant planets evolved outside the ice line because this is where solid ices were available for accretion.
60. The characteristics of an accretionary disc that increase with distance from the Sun.
1. the ice line is further away
2. density of gas and disc decreased with distance from sun ( a jump at ice line)
3. the mass available to build planets increases with distance from sun( because larger orbital circumferences)
61. Why gas giants need to form in the first 3-10 million years of the Solar System.
because the solar wind from new stars quickly clears an accretionary disc of hydrogen and helium gas. ( most got push out by solar wind)
62. Why the cores of Uranus and Neptune grew slower than that of Saturn and Jupiter.
their core is smaller because
1. less material available because the density of the accretionary disc dropped off very rapidly beyond Saturn.
2. collisions between objects happened less frequently because of the larger distance between
objects
3. Jupiter and Saturn captured or ejected material from their orbits, stunting their growth.
63. Why Uranus and Neptune are called Ice Giants.
they collect a lot of ices to develop large icy mantles (still collect some hydrogen and helium)
(the mantles of urans and neptune are comprised of very hot liquid water, ammonia, and methane, compounds that have low melting temperature(volatiles), referred to as ices.
64. Uranus' original name for 70 years.
George
65. Why Ceres is a sphere.
it is big enough, the gravity is strong enough to overcome the strength of rock and ice and
pull the body into sphere.
66. Why Haumea is an oblate spheroid.
it rotates very fast that the inertia forces cause it to be very elongated. (it would be a sphere if it is not spinning)
67. Why the heights of plateaus and mountains on celestial bodies are limited.
pressure caused by gravity causes rocks to break or flow
68. Why Mars has taller and deeper topography than Earth and Venus.
relatively small gravity
69. Whether surface gravity always points toward the center of a celestial body.
no, if a body is too small to pull itself into a sphere
Unit 3: Planetary Motions
70. Where the angular velocity of a rotating accretionary disc is fastest.
within the disc (smallest orbital radius) (conservation of momentum)
71. What conservation of angular momentum leads one to expect regarding the spin of planets.
4
the sun should rotate fastest not true> magnetic field
inner rotates faster ( also true within the asteroid belt)
72. Why the axes of rotation of the planets are not found to align perpendicular to the ecliptic.
1. gravitational interactions with each other
2. violent impacts during accretion
3. offset of the center of mass and the geometrical center a planet (center of mass moves due to glaciation, mantle convection, and plate tectonics)
73. Why the tilt of Mars varies significantly more than the tilt of Earth.
1. mars is smaller than Earth, more easily influenced by changes to its mass distribution from
volcanism.
2. mars is smaller and closer to Jupiter and Saturn, magnifying their effect of mar's tilt
3. mars does not have a large stabilizing moon like earth 74. Why the spin rates of the giant planets are faster than that of Earth.
They are more massive
( more angular momentum transferred from the accretion disc into a smaller region, leading to faster rotations)
75. Why Mercury and Venus spin so slowly.
because their close proximity to the sun that caused them to be nearly tidally locked to sun
76. The differences between neap and spring high tides.
spring tide: when the moon and sun tides align, high tides are highest and low tide are lowest
(occur with new and full moon)
neap tide: moon and sun tides are perpendicular, high tides are lowest, low tides are highest
77. The number of times the Moon rotates about its spin axis during each orbit around the Earth.
1 (one side of moon always face Earth, known as tidal locking, caused by gravitational forces)
78. What tidally locking means with regards to observing Earthrise from the lunar surface.
the earth appears stationary on the surface of the moon
79. Why the Moon is fully tidally locked but Mercury is not.
Jupiter’s gravity is strong enough to elongate mercury's orbit causing it to rotate 1.5 times (moon is perfectly tidally locked because it remains in circular orbit)
80. The center of Aristotle’s universe.
earth
81. Copernicus’ great contribution to science.
place sun at the center and assumed to have circular orbit
82. The major breakthrough that allowed Kepler to explain the orbits of celestial bodies.
elliptical orbit >3 laws of planetary motion 83. How eccentricity, e, varies from a circle to an infinite ellipse.
0(circle)=<e<1(highly elliptical)
84. How Neptune was discovered.
Uranus was not following the second law, another planet's gravity was tugging on it.
85. What Keppler’s second law says about how the speed of a planet varies in its orbit.
a line that connects a planet to the sun sweeps out equal areas in equal times (accelerate when
closer to sun, decelerate when further from sun)
86. According to Kepler’s 3
rd
Law, the factors that influence the time it takes a planet to orbit.
the square of the period of any planet is proportional to the cube of the radius of its orbit
(P^2 a r^3)
87. The two forces that determine a planet or moon’s orbital parameters. gravity and centrifugal force
(angular velocity creates a centrifugal force that serves to throw an orbiting object outwards)
88. What happens if you launch from a planet with too little angular velocity.
pull in 89. What happens if you launch from a planet with too much angular velocity.
5
fly out
(orbit: balance of gravitational force and centrifugal force)
90. The geometry that defines the transition to an escaped orbit.
e=1 parabola (not orbiting> hyperbola)
91. How we know that our 2017 interstellar visitor Oumuamua was not here to stay.
because its trajectory traces a hyperbola (high angular velocity)
92. The manner in which angular velocity varies with orbital height for Earth satellites.
the satellites orbit more slowly the more distant they orbit (Kepler's third law)
(orbital distance of a satellite can be changed by changing the orbital speed)
93. The parameters used to measure the mass of a planet based on the orbit of a moon.
balance between centrifugal force and gravity
(mass of moon is not relevant) GMm
/r^2=w^2rm
(
all need to know is orbital distance(r) and angular velocity(w) of one of its moon)
94. What a hot Jupiter is.
gas giants similar in size to Jupiter but orbiting very close to their stars
(seems to contradict the ice line theory of formation)
> hot Jupiter’s formed beyond their solar system's ice line and then migrated inwards
( caused by gravitational interactions)
95. What a rogue planet is.
no longer orbit the sun
(it travels unbound through the galaxy)
96. What an orbital resonance is.
occur when two or more bodies orbit at multiples of a common period.
(stable (remain in orbit) usually result from the larger body being circular orbit, and unstable (push out of the orbit)from being elliptical)
97. Why there are gaps in the asteroid belt.
caused by unstable resonances. (any asteroid in these orbits are kicked out by Jupiter’s gravity)
98. How Jupiter and Saturn moved during the Grand Tack.
formed beyond ice line, then moved towards to sun because of drag, and then moves further away to their present positions because of orbital resonances.
99. The possible consequences of the Grand Tack.
- when Jupiter and Saturn moved outwards, gravitational interactions caused Uranus and Neptune to move further out as well
- as Jupiter and Saturn moved inward, most of the objects in solar system were ejected (unstable orbital residences with asteroids)
(asteroid belt has very little mass and lots of ice, mars did not grow much bigger, Uranus and Neptune have distant orbits)
100. The possible consequence of the future flyby of the star Gliese 710.
will pass close enough to perturb the Oort cloud, sending showers of comets into inner Solar system for millions of years, triggering visibility of about ten naked-eye comets per year, and
possibly causing an impact event
6
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