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Astronomy > Final Exam > Flashcards

Final Exam Flashcards

1
Q

what is an archaea or an extremophiles?

A

bacteria that can survive in extreme conditions.

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2
Q

why do we look for microbes in extreme conditions?

A

because we want to see if microorganisms can live in higher radiation conditions of Jupiter.

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3
Q

when did life come to be?

A

very close after earth was born.

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4
Q

why was first life under water?

A

because we could only develop once ozone layer formed.

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5
Q

what is the primary topic of the general theory of relativity?

A

the general theory of relativity is primarily a theory of gravity, stating that the force of gravity arises from distortions of spacetime.

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6
Q

what is spacetime?

A

the four-dimensional combination of space and time that forms the “fabric” of our universe.

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7
Q

what are the three possible geometries of spacetime?

A

flat geometry, spherical geometry, and saddle-shaped geometry.
flat - ordinary laws of flat geometry apply.
spherical - lines start out parallel tend to converge
saddle-shaped - lines that start out parallel tend to diverge.

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8
Q

what is doppler shift?

A

shift in the wavelength of an objects light caused by its motion toward or away from us.

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9
Q

what do we learn from a redshift or blueshift?

A

it tells us how fast the object is moving away from us (red) or toward us. (blue) The Doppler shift does not tell us about motion across our line of sight.

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10
Q

what does the doppler shift apply to?

A

sound and light.

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11
Q

velocities away from observer shift light to ___ for red or blue?

A

red.

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12
Q

velocities toward observer shift light to ___ for red or blue?

A

blue.

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13
Q

the higher the velocity….?

A

the larger the shift.

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14
Q

what are the life stages of a low-mass star?

A

spends most of its life generating energy by fusing hydrogen in its core. Then it becomes a red giant, with a hydrogen shell burning around an inert helium core.

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15
Q

how does a low-mass star die?

A

like the Sun, never gets shot enough to fuse carbon in its core. It expels its outer layers into space as a planetary nebula, leaving behind a white dwarf.

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16
Q

what are the life stages of a high-mass star?

A

lives much shorter life than a low-mass star, fusing hydrogen into helium. After exhausting its core hydrogen, a high-mass star begins hydrogen shell burning and then goes through a series of stages burning successively heavier elements. The furious rate of this fusion makes the star swell in size to become a supergiant.

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17
Q

how do high-mass stars make the elements necessary for life?

A

in the final stages, a high-mass’s core becomes hot enough to fuse carbon and other heavy elements. The variety of different fusion reactions produces a wide range of elements - including all the elements necessary for life - that are then released into space when the star dies.

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18
Q

how does a high-mass star die?

A

explodes in a supernova and scatters newly produced elements into space and leaves a neutron star or a black hole behind.

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19
Q

when does a supernova occur?

A

after fusion begins to pile up iron in the high-mass star’s core. Iron fusion cannot release energy, therefore the core cannot hold off the crush of gravity for long. Once the gravity wins, the core collapses and the star explodes.

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20
Q

how does a star’s mass determine its life story?

A

determines how it lives. Low-mass won’t get hot enough to fuse heavier elements and they end their lives by expelling their outer laters and leaving a white dwarf behind.
Whereas high-mass stars live short but brilliant lives, ultimately dying in supernova explosions.

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21
Q

how are the life of stars with close companions different?

A

when one star in a close binary system begins to swell in size at the end of its hydrogen-burning life, it can begin to transfer mass to its companion. This mass exchange can then change the remaining life histories of both stars.

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22
Q

what happens to a white dwarf when it accretes enough matter to reach the ___ M sun limit?

A

1.4, it explodes.

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23
Q

what is a white dwarf?

A

core leftover from a low-mass star, supported against the crush of gravity by electron degeneracy pressure.

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24
Q

what can happen to a white dwarf in a close binary system?

A

a white dwarf in a close binary system can acquire hydrogen from its companion through an accretion disk. As hydrogen builds up on the white dwarf’s surface, it many ignite with nuclear fusion to make a nova.

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25
Q

what best describes the features of our solar system?

A

the nebular theory.

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26
Q

where is the asteroid belt between Mars and Jupiter?

A

main asteroid belt is between the two and orbit with scattered pieces of rock left over. Called planetoids or asteroids, meaning “star-like”.

27
Q

what is the habitable zone?

A

it can have water (liquid) meaning it is warm enough.

28
Q

what is the order of the planets?

A

M V E M J S U N

29
Q

what are the two types of planets?

A

terrestrial (rocky) and jovian (gas)

30
Q

what planet is the hardest to see?

A

mercury.

31
Q

what type of celestial object did Edwin Hubble observe to measure the distance to Andromeda Galaxy?

A

Cepheid variable stars.

32
Q

what is the evidence for dark matter in galaxies?

A

the orbital velocities of stars and gas clouds in galaxies do not change much with distance from the centre of the galaxy. Applying Newton’s laws to these orbits leads to the conclusion that the total mass of a galaxy is far larger than the mass of its stars. Because no detectable visible light is coming from this matter, we call it dark matter.

33
Q

why do we call it dark matter?

A

because there is no visible light comes from it.

34
Q

why do we assume when we use a “standard candle” or “standard bulb” to find distance?

A

because light intensity is inversely proportional to distance squared, we know the luminosity of the “standard candle.”

35
Q

rotational velocity of a spiral galaxy is related to what other characteristic?

A

intrinsic luminosity.

36
Q

Hubble’s law describes what type of relationship?

A

velocity-distance.

37
Q

what data on a galaxy is necessary to use Hubble’s Law as a distance indicator?

A

redshift in the galaxy’s spectrum.

38
Q

what are the necessities for life?

A

nutrient source (which is all around the galaxy), energy (sun, internal heat, chemical reactions), and liquid (water or some other source).

39
Q

what is life on Earth based on?

A

it is carbon-based.

40
Q

what is the mass of the Sun?

A

much bigger mass than any other in the solar system, contains more than 99.8% of solar system.

41
Q

our Sun is ___ x the diameter of the Earth.

A

100.

42
Q

what type of star is the Sun?

A

G2 star.

43
Q

what does extrasolar planets mean?

A

means they are an extra planet outside our system.

44
Q

where do asteroids and comets come from?

A

from the Sun’s blow out of gases and junk that is leftover from the accretion process.

45
Q

why are their two types of planets?

A

it comes from their temperature.

46
Q

how did the nebular theory form?

A

formed from the gravitational collapse of solar nebula.

47
Q

in the OBAFGKM, which lives the longest and which the shortest?

A

from shortest to longest.

48
Q

why do we use radio waves?

A

because it penetrates through gasses.

49
Q

how old is the Earth and how old is the oldest rock found?

A

4.6 GYR and the oldest rock is 3.8 billion years.

50
Q

what is Saturn’s largest moon?

A

Titan.

51
Q

what does the value of Hubble Constant tell us?

A

the rate at which the universe is expanding.

52
Q

how is Hubble constant related to the age of the universe?

A

the age of the universe is the inverse of the Hubble constant.

53
Q

what effect does gravity have on the expansion rate of the universe?

A

gravity tends to decrease the rate of expansion.

54
Q

what evidence suggests that the universe’s rate of expansion is increasing?

A

distant type 1a supernova explosions are dimmer than expected.

55
Q

what is the age of the universe roughly?

A

14 billion years. (13.8B)

56
Q

what is the fate of the universe, based on the rate of expansion and changes in the rate of expansion?

A

the universe will expand forever at an increasing rate.

57
Q

how does the temperature and density of the early universe compare to these same conditions today?

A

the early universe was hotter and denser.

58
Q

contents of the universe?

A

5% atoms, 27% cold dark matter (elementary particles as yet undiscovered on Earth), 68% mysterious “dark energy” (we aren’t even sure of the physics of this substance)

59
Q

composition of the universe?

A

75% hydrogen, and 25% helium.

60
Q

what does the milky way contain?

A

bulge and halo, bulge has dust and gas, halo has little gas.

61
Q

where do stars tend to form in our galaxy?

A

in the spiral arms typically as the gas clouds crash into each other and compresses them thus making a star.

62
Q

what is in the centre of our galaxy?

A

a black hole about 3-4 million times as massive as the Sun.

63
Q

what is Hubble’s law?

A

tells us more-distant galaxies are moving away faster: where is Hubble’s constant. It allows us to determine a galaxy’s distance from the speed at which it is moving away from us, which we can measure from its Doppler shift.

Astronomy (4 decks)

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