Planets

Question 1

What is the name of the organisation which define what is and isn’t a planet?

Answer 1

The International Astronomical Union (IAU)

Question 2

What three things define a celestial body in our solar system to be a planet?

Answer 2

1) it is in orbit around the sun
2) it has sufficient mass for its self-gravity to overcome rigid body forces so that it assumes a hydrostatic equilibrium (nearly round) shape
3) it has cleared the neighbourhood around its orbit

Question 3

Name the two ‘inferior’ planets.

Answer 3

Mercury and Venus (as they are closer to the Sun than Earth)

Question 4

Name the ‘superior’ planets.

Answer 4

Mars, Jupiter, Saturn, Uranus and Neptune (plus dwarf planets such as Pluto and Ceres) - all are further from the Sun than Earth

Question 5

Name the ‘inner’ planets.

Answer 5

Mercury, Venus, Earth and Mars (as they are all inside the asteroid belt, rocky or terrestrial planets)

Question 6

Name the ‘outer’ planets.

Answer 6

Jupiter, Saturn, Uranus and Neptune (as they are all outside the asteroid belt, gas giants)

Question 7

Who proposed the ‘Planet X hypothesis’ at the start of the 20th Century, stating that there might be another planet beyond Neptune based on discrepancies in gas giant orbits?

Answer 7

Percival Lowell

Question 8

What is the name for a planetary-mass object that has either been ejected from the solar system or was never gravitationally bound to any star, so therefore orbits the galaxy directly?

Answer 8

Rogue planet or orphan planet

Question 9

What is a name for a planet which orbits two stars instead of one?

Answer 9

Circumbinary planet

Question 10

What was the name of the planet, proposed by 19th-century French mathematician Urbain Le Verrier to be situated between Mercury and the Sun to explain discrepancies in Mercury’s orbit?

Answer 10

Vulcan

Question 11

Who proposed the small planet ‘Vulcan’ between Mercury and the Sun to explain discrepancies in Mercury’s orbit?

Answer 11

Urbain Le Verrier

Question 11

Whose laws of planetary motion describe the motion of planets around the Sun?

Answer 11

Johannes Kepler

Question 11

What is the name of the now-discredited hypothesis that the semi-major axes of planets in the solar system follow a simple rule?

Answer 11

Titius-Bode Law (or just Bode’s Law) - the discovery of Neptune discredited it

Question 12

What is the name for the difference between the equatorial and polar diameters of a planet due to the centrifugal force of its rotation?

Answer 12

The Equatorial Bulge (Earth’s is 42.7 km)

Question 13

What is the name for Earth’s not-quite-spherical shape?

Answer 13

Oblate Spheroid

Question 14

Which planet has an orbital period (year) of just 88 days?

Answer 14

Mercury

Question 15

Which planet has an average temperature of 167C?

Answer 15

Mercury

Question 16

How many moons does Mercury have?

Answer 16

0

Question 17

What is the second densest planet, after Earth?

Answer 17

Mercury

Question 18

What is the second hottest planet, after Venus?

Answer 18

Mercury

Question 19

Which two moons of the solar system are larger than Mercury?

Answer 19

Ganymede (Jupiter) and Titan (Saturn)

Question 20

Which planet has the highest orbital eccentricity?

Answer 20

Mercury (7 degrees)

Question 21

Which is the fastest planet?

Answer 21

Mercury (48 km/s)

Question 22

What is the name for the largest crater on Mercury which measures about 1550 km in diameter, making it one of the largest impact basins in the solar system?

Answer 22

Caloris Basin (or Caloris Planitia)

Question 23

Which planet has an orbital period (year) of 225 days?

Answer 23

Venus

Question 24

Which planet has the highest average temperature (462C)?

Answer 24

Venus

Question 25

Which planet has an atmosphere consisting of 96.5% carbon dioxide?

Answer 25

Venus

Question 26

How many moons does Venus have?

Answer 26

0

Question 27

Which is the closest planet to Earth?

Answer 27

Venus

Question 28

What are the three alternative names for Venus?

Answer 28

Hesperus (evening star), Lucifer (morning star) or Phosphorus

Question 29

Which two planets have retrograde rotation?

Answer 29

Venus and Uranus

Question 30

On which planet is a day longer than a year?

Answer 30

Venus (year: 225 days, day: 243 days)

Question 31

Which acid makes up the acid rain found on Venus?

Answer 31

Sulphuric acid

Question 32

Which celestial object is the brightest in the night sky, after the moon?

Answer 32

Venus

Question 33

Which planet has the lowest orbital eccentricity?

Answer 33

Venus

Question 34

Who was the first to observe the transit of Venus, and in what year?

Answer 34

Jeremiah Horrocks in 1639

Question 35

Who first hypothesised that Venus could have an atmosphere in 1761?

Answer 35

Mikhail Lomonosov

Question 36

When was the last transit of Venus, and when will the next one be?

Answer 36

2012 and 2117

Question 37

What is the rarest predictable astronomical phenomenon?

Answer 37

Transit of Venus

Question 38

Where did James Cook observe the 1769 transit of Venus from?

Answer 38

Point Venus in Tahiti

Question 39

What is the name for the 'teardrop' effect which occurs between the second and third contacts of the transit of Venus, which makes it impossible to accurately time those contacts?

Answer 39

Black drop effect

Question 40

Which mountain massif contains the highest point on the surface of Venus, and on which terra is it?

Answer 40

Maxwell Montes on Ishtar Terra (named for James Clark Maxwell)

Question 41

What group are every Venus surface feature named after?

Answer 41

Women or goddesses (except Maxwell Montes, Alpha Regio and Beta Regio)

Question 42

What is the name of the highest volcano on Venus?

Answer 42

Maat Mons

Question 43

Which is the only planet not named after a god?

Answer 43

Earth

Question 44

What was the length of the day when Earth formed?

Answer 44

6 hours (as rotation speed was faster)

Question 45

At what angle is the Earth's rotation axis tilted from the perpendicular of its orbital plane?

Answer 45

23.4 degrees

Question 46

On what date is the Earth closest to the Sun?

Answer 46

3rd January

Question 47

On what date is Earth farthest from the sun?

Answer 47

4th July

Question 48

Which is the densest planet in the solar system?

Answer 48

Earth

Question 49

How old is the Earth?

Answer 49

4.5 billion years

Question 50

What is the temperature at Earth's core?

Answer 50

4000C

Question 51

Approximately what percentage of the volume of the Earth does the crust occupy?

Answer 51

1%

Question 52

What is the most abundant element of the Earth's crust?

Answer 52

Oxygen (46%), followed by silicon (27%) and aluminium (8%)

Question 53

What is the name for the belt of energetic charged particles around Earth which is held in place by the magnetic field?

Answer 53

Van Allen radiation belt (it is formed of electrons in the outer belt and a combination of electrons and protons in the inner belt)

Question 54

What area of the Earth experiences higher than usual levels of radiation due to it being where the Van Allen radiation belt comes closest to the surface?

Answer 54

South Atlantic Anomaly

Question 55

Which planet's day is roughly the same length as Earth's?

Answer 55

Mars

Question 56

Why does Mars have a very thin atmosphere?

Answer 56

It lost it's magnetosphere, so solar wind interacts directly with the ionosphere, stripping away much of the atmosphere

Question 57

What is the tallest known volcano and mountain in the solar system?

Answer 57

Olympus Mons, Mars

Question 58

Who first observed 'canals' on Mars' surface in 1877 (though these are now known to not exist)?

Answer 58

Giovanni Schiaparelli

Question 59

What is the largest visible impact crater known in the solar system?

Answer 59

Hellas Planitia, Mars' southern hemisphere

Question 60

What is the largest recognised impact crater in the solar system (not visible)?

Answer 60

Utopia Planitia, Mars

Question 61

What is the largest known canyon in the solar system, which runs 7 km deep for more than 4000 km along Mars' surface?

Answer 61

Valles Marineris

Question 62

What are the names of the two largest volcanic regions on Mars?

Answer 62

Tharsis and Elysium Planitia

Question 63

What are the names of the moons of Mars?

Answer 63

Phobos and Deimos

Question 64

How many moons does Mars have?

Answer 64

2

Question 65

Which planet has the shortest day, at less than 10 hours?

Answer 65

Jupiter

Question 66

How many moons does Jupiter have?

Answer 66

80

Question 67

Which is the largest planet in the solar system?

Answer 67

Jupiter

Question 68

Which satellite was the first to observe Jupiter's atmosphere, in 1979?

Answer 68

Voyager 1

Question 69

Which gas giant is known for lightning in the atmosphere?

Answer 69

Jupiter

Question 70

Which planet has the highest gravity?

Answer 70

Jupiter

Question 71

What is the name of the large storm visible on the surface of Jupiter?

Answer 71

Great Red Spot

Question 72

Which planets have rings?

Answer 72

Jupiter, Saturn (by far the most visible), Uranus and Neptune

Question 73

What are all of Jupiter's moons named after?

Answer 73

Figures in the life of Zeus (Galilean moons are all lovers)

Question 74

What are the names of the Galilean moons, discovered in 1610 by Galileo?

Answer 74

Ganymede, Callisto, Io, Europa

Question 75

What are the three largest moons in the solar system?

Answer 75

Ganymede (Jupiter), Titan (Saturn) and Callisto (Jupiter). Ganymede and Titan are both bigger than Mercury

Question 76

How many moons does Saturn have?

Answer 76

83

Question 77

Which planet has the lowest density?

Answer 77

Saturn

Question 78

Which planet has the largest equatorial bulge?

Answer 78

Saturn

Question 79

What is the most distant planet that can be seen with the naked eye?

Answer 79

Saturn

Question 80

What is the name of the storm that is visible on Saturn's surface once every 30 years?

Answer 80

Great White Spot

Question 81

What is Saturn's upper atmosphere mostly made of?

Answer 81

Clouds of ammonia ice

Question 82

Who was the first to observe the rings of Saturn in 1610?

Answer 82

Galileo Galilei (although he couldn't identify what they were)

Question 83

Who was the first to suggest that Saturn was surrounded by detached rings of material?

Answer 83

Christian Huygens

Question 84

What is the name of the region between Saturn's A Ring and B Ring? It was discovered in 1675 and is governed by the moon Mimas.

Answer 84

Cassini Division

Question 85

What are the three main rings of Saturn?

Answer 85

A Ring, B Ring and C Ring

Question 86

What is the name of the gap in Saturn's rings at the inner edge of the Cassini division?

Answer 86

Huygens Gap

Question 87

Which gap of Saturn's A ring is caused by the presence of the small moon Pan?

Answer 87

Encke Gap

Question 88

Which gap of Saturn's A ring is caused by the presence of the small moon Daphnis?

Answer 88

Keeler Gap

Question 89

What is the name for the separation between the A ring and F ring? It is named after a French physicist.

Answer 89

Roche Division (after Edouard Roche)

Question 90

Which ring of Saturn is the most active in the solar system and is held together by the orbits of the moons Prometheus and Pandora? It was discovered in 1979 by Pioneer 11.

Answer 90

F Ring

Question 91

What shape is the wave pattern of the jet stream of Saturn?

Answer 91

Hexagonal (around the north polar vortex)

Question 92

How many moons does Uranus have?

Answer 92

27

Question 93

What is the name of the largest moon of Saturn?

Answer 93

Titan

Question 94

What is the name of the largest moon of Uranus?

Answer 94

Titania

Question 95

What was the original name of Uranus?

Answer 95

Georgium Sidus or the Georgian Planet (in honour of King George III)

Question 96

Which is the only planet whose name derives from Greek mythology?

Answer 96

Uranus

Question 97

Which planet has an axis of rotation on its side with respect to the plane of the solar system? This gives it seasonal changes unlike those of other planets?

Answer 97

Uranus

Question 98

Which two planets are often known as the Ice Giants?

Answer 98

Uranus and Neptune

Question 99

What is the name of Uranus' brightest ring?

Answer 99

Epsilon ring

Question 100

Who first observed Uranus in 1781?

Answer 100

William Herschel

Question 101

Which US space observation platform confirmed the presence of a ring system around Uranus in 1977?

Answer 101

Kuiper Airborne Observatory

Question 102

How many moons does Neptune have?

Answer 102

14

Question 103

What is the largest moon of Neptune?

Answer 103

Triton

Question 104

Which two scientists predicted the existence of Neptune from calculations based on observations of Uranus? They did so at the same time without knowing of the other.

Answer 104

Urbain Le Verrier and John Couch Adams

Question 105

Which two scientists observed Neptune using the Berlin Frauenhofer refractor in 1846 based on Le Verrier's calculations?

Answer 105

Johann Galle and Heinrich d'Arrest

Question 106

What makes Uranus and Neptune appear blue?

Answer 106

Methane in the upper atmosphere observes red light

Question 107

Which planet has the strongest sustained winds of any planet?

Answer 107

Neptune

Question 108

What is the name of the spot on Neptune's surface that was discovered by Voyager 2 in 1989?

Answer 108

Great Dark Spot (although this has now disappeared, and there is now a Northern Great Dark Spot in the northern hemisphere)

Question 109

What are Neptune's rings named after?

Answer 109

Astronomers that did important work on the planet - Galle, Le Verrier, Lassell, Arago and Adams