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Astronomy > Lectures 13-16 > Flashcards

Lectures 13-16 Flashcards

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1
Q

How did the jovian planets form?

A
  1. frozen hydrogen compounds (ices) formed planetesimals= build up proto-planets
  2. Massive planets gravitationally attract H and He gas
  3. Solar nebula less dense further out= takes longer to accumulate mass
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2
Q

Describe Jupiter’s internal structure.

A 
top-down:
gaseous hydrogen
liquid hydrogen
metallic hydrogen
core of rock, metals and hydrogen compounds
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3
Q

Does Jupiter emit more heat than it receives?

A

yes- also Saturn and Neptune

-probably due to continued contraction

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4
Q

Explain the red bands on Jupiter’s surface.

A 
red= lower altitude, warmer, emit more IR
white= higher altitude clouds, cooler, emit less IR
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5
Q

How does the atmosphere of Jupiter compare to the Earth’s?

A
  • similar regions: thermosphere, stratosphere, troposphere but no surface
  • features persist longer as there is no friction
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6
Q

What is the Jupiter’s Great Red Spot?

A

-giant storm, long lived, like a hurricane but high pressure

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7
Q

Can magnetic field tell us about the internal structure of a planet?

A

-yes

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8
Q

Why is Jupiter’s magnetic field different?

A

-huge, interaction with IO that’s basically in the magnetic field

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9
Q

What are the two categories of jovian moons?

A

1: formed in accretion disk around planet, larger, regular orbits, surfaces, lots of ice
2: captured- smaller, irregular shapes, little geological activity, irregular orbits

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10
Q

Is Io geologically active?

A

Yes, volcanoes, lot of activity due to tidal stress.

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11
Q

Why are the orbits of the Galilean moons elliptical?

A

because of their orbital resonances

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12
Q

Which place in the solar system is most likely to have life?

A

Europa. -ocean?

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13
Q

Describe the atmosphere of Titan.

A

Thick N2 atmosphere.

  • CH4, C2H6 give greenhouse effect
  • organic molecules
  • lakes of liquid methane and ethane
  • similar geology to Earth
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14
Q

Do all jovian planets have rings?

A

Yes.

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15
Q

How thick and how wide are Saturn’s rings?

A

10 m thick

140 000 km wide

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16
Q

What causes the bands in the rings?

A

Bigger objects sweeping it gravitationally.

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17
Q

A very bright ring will be denser or less dense?

A

denser

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18
Q

What are asteroids?

A

Rocky leftovers of planet formation.

-small more common than big ones

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19
Q

What is the name of the largest asteroid and how big is it?

A

Ceres

1000km in diameter

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20
Q

Would all the asteroids in the solar system add up to a planet?

A

No, not even a terrestrial one.

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21
Q

What are the physical characteristics of asteroids?

A

Not round, cratered

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22
Q

Describe asteroid orbits.

A

Most asteroids in the asteroid belt between Mars and Jupiter.
Trojan asteroids= follow Jupiter’s orbit

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23
Q

How do we call asteroids that cross Earth’s orbit?

A

near earth asteroids

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24
Q

How does Jupiter influence the asteroid belt?

A

Asteroids in orbital resonance with Jupiter experience periodic gravitational tugs.
=this creates gaps in the asteroid belt
-tidal forces from Jupiter prevented a planet forming

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25
What is a meteorite?
A rock from space that falls through Earth's atmosphere.
26
What is a meteor?
The bright trail left by a meteorite.
27
Describe a comet.
- icy counterpart of an asteroid - nucleus is a dirty snowball - most comets remain in deep freeze in the outer solar system - comets have a tail only when they get close to the Sun and start melting
28
What is a coma in a comet?
The atmosphere that comes from a comet's heated nucleus.
29
What is a plasma tail?
Gas escaping from coma, pushed by solar wind.
30
What is a dust tail?
Pushed by photons. always facing away from the Sun.
31
How long are tails of comets approx?
100 000kms long
32
How big is an average comet?
10 km.
33
What is the relationship between a comet and a meteor shower?
The comets leave behind small particles that shower down on Earth and cause meteor showers.
34
Where were the comets first formed?
Between Jupiter and Neptune.
35
Where did comets go after their creation and why?
Influence of the jovian planets gravity, some went to the inner solar system and more in to the outer solar system= Oort cloud/Kuipier cloud= deep freeze
36
What is Oort cloud?
Region rich in comets, trillions 50 000 AU away -comets have eccentric orbits and random tilts
37
What is the Kuiper belt?
30-50 AU - about 100 000 comets more than 100km big - comets orbit in the same plane and direction as the planets
38
How did comets come to be in the Oort cloud and Kuiper belt?
Oort- came from the jovian region | Kuiper- formed here
39
How do comets get to the inner solar system?
When Kuiper or Oort disturbed gravitationally.
40
When did the 3 mass extinctions occur on Earth and how much of life disappeared?
1- 434 million yrs ago 85% life wiped 2- 251 million yrs ago 97% life wiped 3- 65 million yrs ago 70-80 % life wiped -know from fossil record and coral reef growth
41
What role does Iridium play in telling when giant impacts occurred?
- very rare on Earth, often in meteorites - layer of iridium 65 million yrs ago - dinosaur fossils all below this layer
42
Where did the meteorite that killed off dinosaurs fall?
Mexico.
43
How often is Earth hit?
small impacts- daily | -big ones million yrs apart
44
How do light and matter interact?
Emission Absorption Transmission (transparent objects transmit ligt and opaque objects block = absorb light) Reflection/scattering
45
What does a mirror do to light?
Reflects it in a particular direction.
46
What does a movie screen do to light?
Scatters light in all directions.
47
Describe wavelength.
Distance between the two peaks.
48
Frequency?
number of times per second that a wave vibrates up and down.
49
How to calculate wave speed?
=wavelength x frequency
50
What is light?
Both a particle and a wave.
51
How is light a wave?
It is a vibration of electric and magnetic fields, it interacts with particles through these fields.
52
How is light a particle?
Photons, each has a wavelength and frequency and its energy depends on its frequency
53
what is λ?
λ= wavelength
54
what is f?
frequency
55
what is c? how do you get it?
c= speed of light = λ x f
56
How do you calculate energy of a photon?
``` E= h x f h= Planck's constant 6.626 x 10 to -34 joules/s ```
57
Name the parts of electromagnetic spectrum from shortest waves (highest energy).
``` gamma rays X rays UV visible infrared radio (microwaves are bit of infrared and radio) ```
58
What are the three basic types of spectra?
- emission (peaks) - continuous (smooth) - absorption (dints)
59
What is a continuous spectrum?
The spectrum of common lightbulbs, spans all visible wavelengths without interruption.
60
What is an emission line spectrum?
A thin or low-density cloud of gas emits light only at specific wavelengths that depend on its composition and temperature, producing a spectrum with bright emission lines.
61
What is an absorption line spectrum?
A cloud of gas between us and the light bulb can absorb light of specific wavelengths leaving dark absorption lines in the spectrum.
62
Why does each element have a chemical fingerprint?
Each type of atom has a unique set of energy levels, each transition corresponds to a unique photon energy,frequency and wavelength.
63
How do energy levels of molecules differ from atoms?
Molecules have additional energy and vibrational levels that can make the spectra very complicated. -many of these interactions in the infrared part of the spectrum= ie in our atmosphere the greenhouse interactions
64
What does thermal radiation depend on?
Temperature.
65
What emits thermal radiation?
Nearly all large or dense objects, planets, stars, you...
66
What are the properties of thermal radiation?
1. Hotter objects emit more light at all frequencies per unit area. 2. Hotter objects emit photons with a higher average energy. =also called Blackbody radiation
67
How to interpret actual spectrum?
Look at where is it interrupted from interrupted. What does it emit and absorb. If absorbs blue light= appears red if IR peaks= what temp it is UV emission= indicates hot upper atmosphere What does absorb= CO2 = present
68
How can light tell us speed of an object?
red shift moving away, the more it happens the faster it is. | blue shift= moving towards us
69
What does the Doppler shift tell us?
Only about the part of an object's motion towards or away from us.
70
How does rotation of an object affect the spectral lines?
Faster rotation makes the spectral lines wider.
71
What are the 3 main parts of a telescope?
- collecting area: bigger is better= more photons - focusing device: depends on wavelength (mirror curved= visible, nested mirror= X ray) - detector- records photons
72
What is resolution?
How close can two 2 images be and appear distinct?
73
How does the size of collecting area effect resolution?
The bigger the area= the smaller the separation images you can resolve.
74
How does wavelength affect effect resolution?
Longer wavelengths= worse resolution | -can see blue better than red wavelengths
75
How does the atmosphere (visible light) and ionosphere (for radio waves) effect the resolution?
WIggle causing!
76
What is seeing in atmosphere?
Movement of the light as it comes through atmosphere
77
What are the effects of seeing?
twinkling stars-seeing makes the photons dance around as go through atmosphere sunset red= more atmosphere for the light to go through
78
Why do planets not twinkle?
Because they are bigger for us, too big for the seeing to have an effect.
79
Why do we have mostly optical and radio telescopes on Earth?
They are the wavelengths that get here through the atmosphere.
80
How do we know that the Earth is spinning on its axis?
Open shutter of a telescope=for hours= see the stars move
81
What is an analemma?
The movement of the Sun around the sky- makes figure eight= demonstrates that we don't orbit the Sun in a circle
82
What is the position of the Sun, Moon and Earth at lunar eclipse?
Earth passes between the Sun and the Moon, so the Earth's shadow passes across the Moon.
83
What is the position of the Sun, Moon and Earth at solar eclipse?
Moon passes between the Earth and the Sun blocking out the Sun
84
How do we predict eclipses?
The Saros cycles= every 18 years, 11.3 days Earth,Moon and Sun return to the same symmetry -not easily predictable where it will be visible from fully or partially

Astronomy (6 decks)

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