2 Lunar Disc Flashcards
Name 7 features on the Near side of the Moon:
- Ocean Of Storms
- Copernicus Crater
- Kepler Crater
- Sea Of Crises
- Apennine Mountains
- Sea Of Tranquility
- Tycho Crater
How are Lunar Maria formed?
Lunar Maria were formed by ancient volcano eruptions which caused lava to flow into large basins. Molten lava was able to seep upwards near the edges of the Maria
How were Terrae formed?
Terrae are the lighter parts of the Moon and called the Lunar Highlands. They are composed of Feldspar, which is lighter in colour than the Maria as it has crystallised slower, and also reflects more of the Sun’s light
How are Craters formed?
The Lunar Craters were formed from collisions with asteroids and meteorites on the surface. As the Moon has no atmosphere, there is no protection from incoming missiles
How were the Lunar Mountains formed?
Nearer the edges of the Maria, the mountain ranges were thrust upwards, forming mountains.
How are Lunar Valleys formed?
Lunar Valleys form in between the mountains
How long is the Moons orbit of the Earth?
27.3 days
How long does it take for the Moon to rotate on its axis?
27.3 days
Why can we only see one side of the Moon?
The Moon is tidally locked with the Earth
How much of the Moon can we observe at one time?
59%
Why can we see more than 50% of the Moon?
Lunar Libration
What is up-to-down libration?
Libration Latitude
What is left-to-right libration?
Libration Longitude
How is the Moon’s far side different to the Near side?
The far side is devoid of Maria
How does Libration in Latitude occur?
The Moon’s equator is inclined to the plane of its orbit around the Earth by 1.5°; the plane of the Moon’s orbit is inclined at 5.1° to the ecliptic; this makes the Moon appear very high in the sky which is Libration in Latitude
How does Libration in Longitude occur?
Libration in Longitude occurs from the Moon’s varying speed in its elliptical orbit around the Earth.
What is an Apogee?
The point in the orbit of the moon or of an artificial satellite most distant from the centre of the Earth.
What is a Perigee?
The point nearest the earth’s centre in the orbit of the moon or a satellite
What is the Moon’s mean diameter?
3 500 km
What is the Terminator?
The Terminator is the line that separates light and darkness on the moon
At which times during a solar eclipse can we see Baily’s beads?
Second and Third contact
What scale is used to quantify the colour of a lunar eclipse?
Danjon Scale
How long does it take for the Moon to rotate an angle of 240°?
18 days
Where is the Apennine Mountains located?
The Apennine mountains are located between the Sea Of Serenity and the Sea of Rains
Why does Libration in Longitude occur?
During the Moon’s orbit, the orbital speed changes due to its elliptical orbit. The Moon’s rotation remains constant. This allows the eastern and western limb to be visible during different times of the lunar month.
Which are older: Maria or Highlands?
Highlands
How can you deduce that Highlands are older?
The maria have less craters in them suggesting they are younger as they aren’t old enough to have many craters from old impacts
What is the Terminator?
The line on the Moon between light and dark
Why is it best to observe craters near the terminator?
There is a high contrast around the area which creates exaggerated shadows
How much is the Moon inclined to its orbit by?
The Moon’s equator is inclined to the plane of its orbit around the Earth by 1.5°
How much is the Moon’s orbit inclined to the ecliptic?
The plane of the Moon’s orbit is inclined at 5.1° to the ecliptic
What is tidal locking?
Tidal Locking is when a satellite’s orbital period exactly matches its rotational period.
An example is the Moon. Only on side of the Moon ever faces the Earth
What are the theories regarding the origin of the Moon?
- Giant Impact Hypothesis
- Fission Theory
- Capture Theory
- Co-Accretion Theory
Why does the phases of the Moon occur?
The phases of the Moon occur because the Moon is always 50% illuminated and 50% in darkness.
When the Moon orbits around the Earth, the angle we view the Moon from changes so we see different amounts of light and dark sides of the Moon
What is the Giant Impact Hypothesis?
A large astronomical body (named Theia) struck Earth and the debris cooled and condensed to become the Moon
What is the Fission Theory?
The Earth was spinning so quickly, a part Earth broke off and formed the Moon
What is the Capture Theory?
The Earth and Moon were formed at different places in the Solar System but the Earth captured the Moon by the Earth’s gravitational force
What is the Co-Accretion theory?
The Co-Accretion theory is the theory that the Earth and the Moon formed together at the same time out of material from a solar nebula
Why is the Giant Impact Hypothesis the most accepted theory regarding the origin of the Moon?
The Hypothesis is supported by the Moon’s lack of substances that evaporate (volatiles), the discovery of KREEP-rich rocks on Moon and its small iron core
Why can we see many rings during an Eclipse?
When a large light source casts a shadow of a small object, it results in a dark central shadow with a surrounding lighter shadow
What is a ‘Blood Moon’?
A Blood Moon is when the Moon appears to turn red during a lunar eclipse
Why does the moon ‘Blood Moon’ occur?
When the Moon is completely blocked by the Earth, no light directly reaches the Moon’s surface.
The only light that reaches the surface of the Moon, are the rays that have been refracted from the Earth’s atmosphere and red rays have the longest wavelengths so refract the most and are able to be bent so much that the rays hit the Moon. Therefore, the Moon appears red.
What happens during the First Umbral Contact of a Lunar Eclipse?
This is the time when the Moon first enters the Earth’s Penumbra
What happens during the Second Umbral Contact of a Lunar Eclipse?
This is the time when the Moon is completely in the Umbra
What happens during the Third Umbral Contact of a Lunar Eclipse?
This is the time when the Moon first starts to exit the Earth’s Umbra
What happens during the Fourth Umbral Contact of a Lunar Eclipse?
This is the time when the Moon exits the the Earth’s Penumbra
What are Baily’s Beads?
Small bright spots of Sunlight before and after totality which are caused by the Sun’s rays shining through the valleys on the Moon
What is the diamond ring effect?
When only one of Baily’s beads is visible
Why does the Moon look as if it’s the same size as the Sun?
The Moon and the Sun both roughly have angular diameters of 0.5°
What is Gravitational High Tide?
Gravitational High Tide is when the Moon’s Gravity makes the Earth’s water bulge so it is a high tide when you are facing the Moon
What is Inertial High Tide?
Inertial High tide is when the water that isn’t pulled by the Moon, becomes flung outwards by the Spinning Earth
When is there a Low Tide?
When the Earth spins away from the High tide is when there is low tides
What is Lunar Tide?
When the Tides are controlled by the Moon’s gravity
