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Earth and Space > Unit 5: Possible Alien Life, Asteroids and Comets > Flashcards

Unit 5: Possible Alien Life, Asteroids and Comets Flashcards

1
Q

Fermi’s Paradox (3 Points)

A

If extraterrestrials are so common…

  1. why haven’t they visited?
  2. Why haven’t they communicated with us?
  3. why haven’t they left behind some residue of their existence, such as heat or light or some other electromagnetic offal?
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2
Q

Trying to calculate the probability that extraterrestrial life exists in the universe is quite ____.

A

Complicated

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3
Q

What did Frank Drake create? Was it useful?

A

He created a mathematical equation to account for the conditions required to enable such civilization to develop. None of his variables, except one (rate of star formation) could be formulated with confidence.

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4
Q

SETI

A

Search for Extra-Territrial Intelligncce –> it is the search for existence through radio waves.

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5
Q

Modern issues with SETI

A

That people are shifting away from telecommunications from radio and into buried fiber optics.

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6
Q

If we find a planet that is capable of life 400 light years away, what is the problems…

A

we are seeing that planet 400 years in the past, by the time we send a message to them, life could have been extinct on that planet.

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7
Q

Infinity was invented to account for…

A

the possibility that in a never-­‐ending universe, anything can happen.

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8
Q

According to Prof Watson there is a limit to..

A

evolution is the habitability of Earth, and any other Earth-­‐ like planets, which will end as the sun brightens.

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9
Q

Prof Watson suggests the number of evolutionary steps needed to create intelligent life in case of humans is four. These include:

A
  1. Emergence of Single-Celled Bacteria
  2. Complex Cells
  3. Specialized cells allowing complex life forms
  4. Intelligent life with an established language
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10
Q

Why is intelligent life so much less common according to Prof Watson

A

Complex life is separated from the simplest life forms by several very unlikely steps

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11
Q

Seven Reasons why scientists believe that life is out there..

A
  1. Extremophiles on Earth - organisms that can survive extreme heat, cold and even in vacuum
  2. Evidence of chemical precursors to life on other planets –> the original chemical reactions that brought about life is proven on other planets.
  3. Rapidly expanding # of Earthlike planets–> due to new techniques and better tech.
  4. Sheer diversity and tenacity of life on Earth –> there are many different climates and natural disasters that life managed to survive through (ex. the Ice Age)
  5. Mystery surrounding origin of earth –> there is still mystery on how the chemical reactions occurred to form life.
  6. Growing evidence that oceans and lakes are common –> that are signs of water in our solar system –> mars and saturns moon titan
  7. Evolutionary theory –> suggests that life adapts to its environment thus can adapt to outer space.
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12
Q

Tardigrades

A

are tiny creatures that can survive in the vacuum of space.

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13
Q

Panspermia

A

a theory which suggests that life on Earth arose due to life on other planets

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14
Q

Why is mars likely for life formation

A

had water and is in habitable zone

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15
Q

Does life need water to come about?

A

No, earth has carbon-based life so there is a possibility for other life forms to exist.

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16
Q

Why do we look for water for other planets?

A

It acts like a universal solvent.

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17
Q

How can you tell when a distant planet transits its host star when you can’t see the star?

A

You analyze the wavelengths of the beam of light from that star and when you see a dip, it determines an object has crossed it.

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18
Q

How can they tell how long it would take a planet from another solar system to orbit its host star?

A

When you look at it → it goes from redshift to blueshift back to redshift → one orbit

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19
Q

What materials are in the Kuiper Belt

A

frozen volatiles(gases) such as methane, ammonia, nitrogen and water.

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20
Q

Difference between short-period and long comets?

A

Short Period: Kuiper and orbit sun every less than 200 years.

Long Period: Oort Cloud and orbit sun every more than 200 years.

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21
Q

___ is the farthest object in the solar system ever to be resolved by a telescope.

A

Quaoar

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22
Q

Shape of Kuiper belt

A

disk shaped.

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23
Q

KBO…

A

Kuiper Belt Object

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24
Q

How do we spot far off worlds if we can’t see?

A

Star’s wobble → you can see it redshifting/blueshifting

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25
Q

Oort Cloud shape and why?

A
  • Outer cloud is spherical, inner cloud is disk shaped

- spherical because objects got too close to planets thus were blasted outward in all directions.

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26
Q

Oort cloud’s cloud of particles is theorized to be…

A

the remains of material that formed the Sun and planets.

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27
Q

Hale-Bopp

A

comet that swung near Earth in 1997 and was visible to the naked eye for 18 months. just stood there

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28
Q

Asteroids and comets are considered…

A

remnants from the giant cloud of gas dust

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29
Q

Diff between Asteroids and comets? (4)

A 
Asteroids:
Rocky
Formed close to the sun 
no tail
Shorter, more circular orbits
Comest:
Icy
Formed further from the sun
Tails
Elliptical (egg-shaped) orbits
30
Q

Why do comets have tails while asteroids do not?

A

Because since comets have icey shells, the ice vapourizes when it comes near the sun.

31
Q

Why do comets have icy shells while asteroids do not?

A

because asteroids form closer to the sun where it is too warm for ice to remain solid.

32
Q

What is the largest known TNO (Trans Neptunian Object)?

A

Pluto

33
Q

The largest asteroid is…

A

Ceres

34
Q

Binary Asteroid

A

two rocky bodies of equal size orbit each other

35
Q

Three types of Asteroids…

A
  1. C Type (Carbonaceous): Made of carbonates and are dark. Furthest from sun
  2. S-Type (Silicaeous): made of silicate (stony) material
    closest to sun
  3. M-Type (Metallic): made of nickel-iron
    in between
36
Q

NEO stands for

A

Near Earth Object

37
Q

Why do meteors burn up in the atmosphere?

A

They move so fast, that friction between rock and atmosphere is great.

38
Q

Why is it easier to land on an asteroid than a comet?

A

Asteroids are closer

39
Q

How does a comet form a tail

A

When it warms up near the sun, it develops an atmosphere or coma, surface changes to gas as coma gets bigger, forming a tail

40
Q

Two tails of a comet

A

the dust tail and the plasma tail

41
Q

Meteoroid

A

small pieces of space debris that are on collision course with earth. smaller than asteroids

42
Q

Meteors

A

meteoroid that burns up in the atmosphere. Another name is a shooting star

43
Q

Meteorite

A

Meteoroids that survive the atmosphere and crash into earth

44
Q

Bolide

A

when the meteor burns up

45
Q

Meteor Shower

A

a celestial event in which a number of meteors are observed to radiate from one point in the night sky

46
Q

Only ____ meteoroids make craters

A

only large

47
Q

Chicxulub Crater

A

destroyed the dinosaurs 65 million years ago

48
Q

Would blowing up an meteoroid prevent damage on Earth?

A

No because (1) It would amagaliate (get together) within hours, (2) More damage through more debris

49
Q

How would you prevent an asteroid from hitting earth?

A

Shot a missile to shift it off course (not exploding it)

50
Q

______ are a result of Jupiter’s gravitational field.

A

short-period comets

51
Q

The nucleus of a comet is about ______in radius.

A

16 km

52
Q

The Barringer meteor crater is a mile wide. The asteroid

A

10 yards

53
Q

What effect of a meteor impact may have killed the dinosaurs?

A

the dust blocking sunlight

54
Q

Ceres, the largest asteroid, has a diameter of about

A

1000km

55
Q

Which of the following killed over 15,000 reindeer, and produced a shock measured around the world?

A

Tunguska event

56
Q

Ceres is BEST classified as a(n)__________________.

A

dwarf planet

57
Q

Meteor showers (like the Perseids in August) occur annually when…

A

when Earth crosses the orbit of a comet.

58
Q

If all the asteroids in the asteroid belt were assembled into a planet, it would have a mass ____ than the earth

A

much less than

59
Q

The orbits of comets can… (2)

A
  1. Extend far out beyond Pluto’s orbit.

2. Oriented in any direction

60
Q

When does a comet have the longest tail and largest coma?

A

when it is nearest the sun Think about when comet’s are the hottest.

61
Q

Approximately how large must a meteoroid be in order to survive passage through the atmosphere and reach the ground as a meteorite?

A

as big as a house

62
Q

The particles which produce meteor showers come from

A

dead comets

63
Q

What is the source of the material that causes meteor showers?

A

The nuclei of comets gradually disintegrate and spread out along the comet’s orbital path.

64
Q

What material is found in asteroids?

A

hydrocarbons

65
Q

Why are many of the newly detected extrasolar planets called “hot Jupiters”?

A

Their masses are similar to Jupiter but they are very close to the central star and therefore hot.

66
Q

Why is it highly likely that if life exists elsewhere in the universe that it will be based on carbon chemistry?

A

Carbon is versatile in forming complex, long-chain molecules.

67
Q

Life on earth is carbon-based. Similar molecules could be formed with

A

silicon

68
Q

What organisms alive today is likely to be most similar to the first life forms that evolved on the earth

A

methane-producing bacteria

69
Q

Single-celled organism that thrive in extreme conditions are primarily

A

bacteria

70
Q

What is a major stumbling block for scientific theories about the origin of life on early Earth?

A

How life could arise in the hostile environment of the early Earth.

Earth and Space (2 decks)

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