Topic 2 (The Lunar Disc)

Question 1

What is the shape of the moon

Answer 1

Oblate spheroid

Question 2

What is the mean diameter of the moon

Answer 2

3500km

Question 3

What are the naked-eye lunar formations

Answer 3

.Craters
.Maria
.Terrae
.Mountains
.Valleys

Question 4

Features on the lunar disc

Answer 4

.Sea of tranquility
.Ocean of storms
.Sea of crises
.Tycho
.Copernicus
.Kepler
.Appenine mountain range

Question 5

What formed the maria

Answer 5

The great bombardement after the moon had formed before the cratering

Question 6

What formed the craters

Answer 6

The intermediat cratering after the bombardment

Question 7

What are terrae

Answer 7

The terrae (singular = terra) are the bright areas you see when looking at the Moon. Terrae, called highlands or uplands, make up 84% of the Moon s surface

Question 8

How moon mountains were formed

Answer 8

Convection currents and impact debris

Question 9

How are valleys formed on the moon

Answer 9

When the surface coolded it cracked forming valleys

Question 10

How long does it take for the moon to do a full 360 round the earth

Answer 10

27.3 days the same time it takes for the moon to rotate 360degrees round it’s axis (most large moons show the same behaviour)

Question 11

The fact that the moons rotation round earth and it’s axis occur at the same rate is due to…

Answer 11

Tidal gravitational forces slowing the moon’s periods of rotations till they become tidally locked

Question 12

What is the moons 27.3 day orbit period known as

Answer 12

A sidereal month

Question 13

How much of the moon can we see as the moon orbits the earth

Answer 13

Although the moon has a synchronous orbit we only see the near side of the moon (over a period of time we can observe 59% of its surface due to lunar libration

Question 14

What causes the moons us to see round the moon (libration in latitude)

Answer 14

The moon’s equator is inclined to the plane of its orbit around the earth by 1.5degrees and to the ecliptic by 5.1

Question 15

What does the moon’s equators position cause

Answer 15

the moon’s equators position makes the moon appear high in the sky on occasions and causes libration in latitude

Question 16

What causes us to be able to see further around the moon (libration in longitude)

Answer 16

(Due to Kepler’s second law and the fact that the moon does not orbit the earth in a perfect circle) it takes the moon the same amount of time to travel around each quarter of its orbit round the earth though they are not even in length. This causes libration as the moon faces slightly next to the earth and we can see round the side of it. This is due to its rotation rate not changing