Topic Two: Planetary Systems Flashcards
1
Q
Name the 4 Rocky/Terrestrial Planets:
A
Mercury, Venus, Earth and Mars
2
Q
Name the 4 Gas Giants:
A
Jupiter, Saturn, Uranus, Neptune
3
Q
What is the definition of a planet?
A
A planet is a body that:
- Is in orbit around a Star
- Is large enough to be Spherical
- Has cleared its orbit of other objects
4
Q
Name 6 other types of body in our Solar System except Planets:
A
Asteroids (minor planets) Comets Centaurs Moons/satellites Dwarf Planets TNOs (Trans Neptunian Objects)
5
Q
What size are asteroids?
A
bigger than 10m but smaller than a few hundred kilometres
6
Q
Where are asteroids usually in our solar system? Name a few.
A
The Asteroid Belt
Vesta and Pallas
7
Q
What is the brightest asteroid in the asteroid belt?
A
Vesta
8
Q
What can comets be described as? And what do they consist of?
A
Icy snowballs
Consists of:
Dust, Rock and Ice
9
Q
What are centaurs?
A
Half comet, half asteroid.
10
Q
Where do centaurs orbit?
A
Between Jupiter and Neptune
11
Q
Give examples of centaurs:
A
Chiron, Hidalgo and Absolus
12
Q
Give examples of Dwarf Planets:
A
Pluto, Ceres and Eris
13
Q
What is the IAU?
A
International Astronomical Union
14
Q
What were the 2 decisions the IAU made in 2006?
A
Ceres promoted from Asteroid to dwarf planet
Pluto demoted from planet to dwarf planet
15
Q
What is 1AU?
A
Unit of Measurement
Based on distance between Earth and Sun (150 million km)
16
Q
Describe Mercury:
A
Closest to the Sun Fastest orbital period Heavily cratered Highlands and lava filled basins Smallest Planet
17
Q
What is odd about Venus?
A
It spins backwards (retrograde rotation)
18
Q
Describe Venus:
A
Similar Size to Earth Clouds of Sulphuric Acid Atmosphere of mostly Carbon Dioxide Runaway Greenhouse Effect Temperature: 470 degrees Celsius Pressure: 90x Earth's
19
Q
Describe Mars:
A
Iron rich rocks (red planet)
450km long water carved canyons
Highest volcano is solar system
20
Q
What is the Great Red Spot?
A
The anticyclone weather system greater in size the Earth on Jupiter
21
Q
How many times bigger than Earth is Jupiter?
A
11
22
Q
Describe Jupiter’s equatorial budge:
A
Dynamic wind system splits atmosphere into belts and zones
23
Q
Why does Jupiter have an equatorial budge?
A
Extremely fast rotation (once in only 10hrs)
24
Q
How long is a Venus day?
A
243 Earth days
25
Name some similarities between Uranus and Neptune:
They are both cold Gas Giants
Similar in size
26
Describe some similarities between Jupiter and Saturn:
Both have ring systems
Both are gas giants
Similar rotational periods
27
Describe two differences between Jupiter and Saturn:
Saturn has less visible structure to its atmosphere unlike Jupiter, which as the great read spot, red/brown belts and yellow/white zones
Jupiter's rings aren't as reflective as Saturn's
28
Name some differences between Uranus and Neptune:
Uranus is almost featureless
Uranus spins on its side
Neptune has a Great Dark spot
Neptune has clouds of frozen methane
29
Name 5 problems Astronauts could face is venturing beyond the moon:
Time
Space adaptation syndrome
Physiological problems
Psychological problems
Communication delays
Radiation risk
30
Describe Space Adaptation Syndrome:
- No up and no down
- Disorientation
- Headaches
- Vomiting
- Poor concentration
31
Describe Physiological problems from venturing beyond the moon:
Prolonged zero gravity causes:
- Muscle wasting
- Brittle bones
- Reduced red cell count
32
Name some advantages of robotic planetary exploration:
- Less expense
- No loss of life
- Safer
33
Name one advantage of human planetary exploration:
Hype -publicity, etc
34
Name Mars' two small moons:
Deimos
| Phobos
35
Why do astronomers believe that Deimos and Phobos are captured Asteroids?
Heavily cratered
Irregular in shape
Densities half that of Mars
Compositions similar to asteroids
36
Name 3 moons of Neptune:
Triton
Dark Proteus
Nereid
37
Describe Dark Proteus
Largest irregular moon of the Solar System
| Orbits in the plane of Neptune's equator
38
Describe Nereid:
Highly eccentric orbit:
- 1 orbit is 1 Earth year
- probably captured Kuiper Belt object
39
Why do astronomers believe Triton is also a captured body?
Revolves around Neptune in the opposite direction to Neptune's rotation
Highly inclined orbit
It is thought that Triton's capture is the result of a collision with Neptune or one of its moons
40
Name 4 planets that have ring systems:
Saturn
Jupiter
Neptune
Uranus
41
Why aren't Jupiter's rings visible like Saturn's rings?
Saturn's rings are made out of highly reflective ice particles
Jupiter's rings are made out of dark dust
42
What are the gaps in Saturn's rings called?
The Cassini Division
43
Which planets have incomplete rings (arcs)?
Neptune
| Uranus
44
Give 4 theories on the origin of rings:
Debris left over from planet formation
Large impacts between moons
Moons torn apart through tidal gravitational forces
Meteors striking moons creating debris
45
Are the orbits of planets circular?
No they are elliptical
46
What is the plain on which the planet's orbit called?
The ecliptic
47
What is the Zodiacal band?
Because all the planets orbit on the ecliptic they appear to move through a narrow region of the sky called the Zodiacal band
48
What are the inferior planets?
Mercury and Venus
49
What are the Superior Planets?
Mars to Neptune
50
Where do the inferior planets appear in the sky?
Near the sun
| Best observed during sunsets and sunrises
51
At what time in their orbit is it best for us to see Mercury and Venus?
At their Greatest Elongation
52
What is an inferior conjunction?
When the angle of elongation is 0
Planets passes between Sun and Earth
May undergo a transit
53
What is a superior conjunction?
When the angle of elongation is 0
When the planet passes behind the Sun
May undergo an occultation
54
What is an occultation?
When the planet disappears behind the sun
55
When are superior planets most favourably placed for observation?
Give two reasons why:
At opposition
Brighter (fully illuminated by sun throughout night) and better resolution (closest to Earth)
56
Which directions do planets seem to move in the night sky?
From west to east
57
Explain retrograde motion:
Direct motion of planet seems to stop and move backwards
It is because Planets orbit the sun at different speeds (Angular and Actual)
We therefore see planets from different viewpoints (as we also orbit the sun)
58
What kind of orbits do comets have?
Highly elliptical
59
Describe the ion tail of a comet:
Blue coloured
Fluorescence
Ionised carbon monoxide
Ionised by solar wind
60
What direction does the ion tail point in?
Away from the sun
61
Describe the dust tail of a comet:
```
Lighter coloured
Broader
Curvier
Produced by radiation pressures pushing particles out of the nucleus
Reflects sunlight
```
62
What direction does the gas tail point in?
Away from the path of the comet
63
Name two categories of comets:
Short period
| Long period
64
Describe short period comets:
<200 years
| Originate from Kuiper Belt
65
Describe long period comets:
Originate from Oort Cloud.
Paths clockwise or anticlockwise.
Orbits highly inclined to the ecliptic.
Originate vast distances from the sun.
66
What is the Kuiper belt?
Where short period period comets originate
Disc shaped region of icy bodies
Beyond Neptune
30-50 AU from Sun
67
What is the Oort Cloud?
Where long period comets originate
Spherical region of cometary nuclei
Roughly 50000AU from Sun
68
What is the difference between a meteoroid and meteorite?
A meteroid is a small rocky irregular lump in the solar system
Meteroids are between micrometres and several meters
When a meteroid enters the earth's atmosphere it turns into a meteor
If it survives the atmosphere and impacts the grounds is a meteorite.
METEOROID - METEOR - METEORITE
69
Name three origins of meteroids:
Broken fragments of clodding asteroids
Impacts with the surface of the moon or Mars
The dust tails of comets
70
How fast can a meteoroids orbit be?
40km/s
71
What is a meteoroid shower?
A dramatic increase in the number of meteors observed when the Earth passes through a meteoroid stream left by a comet
72
What causes meteors to appear as light streaks in the sky?
Friction between a meteor and the surrounding air product heat and light
73
What is a fireball?
Meteors with a bright magnitude of -3 or less
74
What is the radiant?
A point in the night sky from which meteors appear to diverge from
75
Describe the classification of meteorites:
Stones, Irons, Stony Iron
76
How do we name meteor showers?
Named after the constellation in which the radiant is found
77
Name 4 annual meteor showers and when they occur:
Perseids - in August
Leonids - in January
Geminids - in December
Quadrantids - in January
78
What is the definition of an NEO?
A near Earth object is an asteroid or comet whose path might bring them closer to Earth than 0.3AU
79
What is a PHO?
A potentially hazardous object
Comes closer than 0.05AU
80
Give examples of collisions between astronomical bodies in the solar system:
Craters
Unusual rotations
Giant Impact Hypothesis
Comet Shoemaker-Ievy
Tunguska event (explosion of comet/asteroid in the sky)
81
Why do we need to monitor PHOs?
Because it could have catastrophic consequences
| Especially if the PHO's are larger than 1km
82
What is the Torino Scale?
Used to assess asteroid/comet impact predictions
83
Who was Ptolemy?
First Geocentric Model of the universe
| Ancient Greece
84
Who was Copernicus?
First Heliocentric model of the universe
85
Who was Kepler?
Tycho's assistant
| Formulated laws of planetary motion
86
Describe Kepler's 1st law:
Planets move in elliptical orbit around a Star
| Star was at one focus of each ellipse
87
Describe Kepler's 2nd Law:
Planets speed is related to distance from Sun
| The closer the sun the faster the orbit
88
Describe Kepler's 3rd Law:
The orbital period of a planet is directly proportional to its mean distance from the sun
T squared = R cubed
Where T =number of Earth years to orbit the sun
Where R = the average distance from the Sun in AU
89
Name some of Galileo's discoveries:
The moon was not spherical
Venus's phases
Four of Jupiter's moons
90
Name the four galilean moons:
Callisto, Europa, Ganymeade and Io
91
Who was Newton?
Came up with the theory of Gravity
Inverse Square Law
92
What is the inverse square law?
two objects are inversely proportional to the square of their distance
Distance between two object doubles, force is one quarter of original value
93
Who discorvered Uranus?
William Herschel in 1781
Mistook Uranus for a star
Tracked the star to find an orbit
94
Who found Ceres?
Giuseppe Piazza in 1801
| Astronomers predicted another planet between Mars and Jupiter
95
Who found Neptune?
Johann Galle and Henrick D'arrest
Based on a mathematical prediction by Le Verrier
96
Describe Astrometry:
When stars wobble due to exoplanet's gravity.
Astronomers monitor stars to see if they wobble, to indicate whether their are exoplanets orbiting
97
Describe Transit method:
When exoplanets move across the star the brightness is reduced.
Astronomers monitor star's brightness and observe light curves.
98
What is a "Hot Jupiter"?
Large planets orbiting at extremely close distances to the parent star
99
What is the main problem with the current methods used to find exoplanets?
We cannot find rocky, Earth-like exoplanets
100
What is the Kepler spacecraft?
NASA space observatory, aiming to find earth sized planets in habitable zone
101
What is the problem with using the Transit method?
We must be in the plane of the exoplanets to detect changes in light
102
What are the two essential chemical ingredients for life (as we know it)?
Carbon and liquid water
103
Where is water on earth thought to have come from?
Deposited by ice containing comets striking Earth
104
What is the habitable zone?
Narrow range of distances from star
Temperature allows liquid water
Goldilocks zone (neither too hot or too cold)
105
What is the Drake Equation?
The estimated probability of life existing elsewhere in our Galaxy
N = R* Fp Ne Fl Fl Fc L
106
List some factors considered in the Drake Equation:
Number of stars in our galaxy
Fraction of stars with planetary system s
Number of planets capable of sustaining life
Fraction of life forms that are intelligent
Fraction of these that can and wish to communicate
Fraction of planets lifetime of which such civilisations can live
107
Where else in our solar system is life most likely?
Mars
| Europa (one of Jupiter's moons)
108
Name 3 techniques astronomers use to search for signs of life on other planets:
Space probes
Spectral analysis of planetary atmospheres of rocky planets
Analysis of radio waves
109
Name 2 potential dangers of finding extra-terrestrial life:
Potential Foes
| Diseases
