The Moon Flashcards
- Identify the Moon‘s principal features, You could be asked to label.
The Sea of Tranquillity, Ocean of Storms, Sea of Crises, the craters Tycho, Copernicus and Kepler, and the Apennine mountain range (Latin names are acceptable).
Recall the Moon‘s diameter
3 500 km
How far is the Moon from Earth
380 000 km 0.003 AU
What is the Moon‘s rotational period and orbital period
27.3 Days
Demonstrate an understanding of why the far side of the Moon is not visible from Earth.
The Moon has a synchronous (or captured) rotation which means that from Earth only one side or hemisphere can be seen.
Describe how astronomers know the appearance of the Moon‘s far-side and how it differs from the near side.
We did not know what the far side looked like until the Soviet Luna 3 probe took pictures of it in 1959. Today the only humans to have viewed it are the Apollo astronauts.
The far side has fewer maria than the near side, it is more cratered. It is thought that the near side has a thinner crust and has had a higher amount of heat-producing elements.
Distinguish between the lunar seas (maria) and highlands (terrae).
Maria appear darker than the terrae as they contain more iron-rich elements. There are few maria on the far side of the moon.
Demonstrate an understanding of the origin of lunar seas and craters.
There was a period called the ‘Heavy Bombardment’ when the Moon (and presumably the inner Solar System) underwent a time of frequent and violent impacts.
Millions of years (sometimes as many as 500 million years) later the Moon underwent a time of volcanic activity and lava was forced to the surface. This lava later turned to basalt. It flooded the lower impact areas and would have covered any other features on the landscape including other craters. The highlands were left untouched.
Demonstrate an understanding that the relative numbers of craters in the seas and highlands implies different ages of these features.
Rocks brought back from the Apollo missions have shown they were formed 3-4 billion years ago.
Describe the nature of rilles and wrinkle ridges.
Rilles are cracks or clefts on the lunar surface notably near maria. They are geological faults caused by collapsed lava tubes. When lava flowed on the Moon, the top and sides of these tubes solidified first while lava flowed underneath. When this lava moved away or solidified, the top or roof of the tube collapsed, leaving these rilles.
Wrinkle ridges are ridges of maria, usually hundreds of kilometres in length. They are not considered mountains, being only around 200 metres high.
Relate the lack of atmosphere to the Moon‘s low gravity.
Without enough gravity a planet or moon would not be able to keep an atmosphere - it would evaporate into space. Saturn’s largest satellite, Titan has an atmosphere because it is larger than our Moon and has a greater mass. It is also much further from the Sun and does not experience the strong solar wind that our Moon does.
Describe the nature and purposes of the Apollo space programme and its experimental packages (ALSEPs).
The Apollo space missions are thought to be the most important manned space missions to date. The reason is that astronauts landed on the Moon, explored it and brought back samples of Moon rocks
The astronauts deployed Apollo Lunar Surface Experiments Package (ALSEPS). These experiments included mirrors left there so we can measure the distance to the Moon by laser, seismographs to measure moonquakes and sensors to measure solar radiation.
Describe the likely origin of the Moon (the giant impact hypothesis).
A Mars size object crashed into the early Earth, changing its axis and jettisoning debris into its orbit and the Moon formed from this.
Describe the evidence that allowed astronomers to develop the giant impact hypothesis.
The relative abundance of the isotopes of oxygen in moon rocks were found to be almost identical to those on earth suggesting they formed at the same distance from the sun
The lack of Water and other volatile compounds in the lunar rocks were similar to those in the earths mantle supporting the idea of a collision involving so much energy that these vapourised during the Moons formation
The Discovery of KREEP-rich rocks in the ocean of storms and Sea of Showers regions of the Moon the hypothesis predicts that an ocean of hot cooling magma would have crystallised in a region below the lunar crust
What dose KREEP stand for?
Potassium, Rare Earth Elements and Phosphorous
