What is true about the Earth and the Moon?

Question

Which ones are true?

1. The Moon lost its atmosphere because of its low gravity.
2. The We think the Earth and Moon are both about 4.6 billion years old.
3. The Earth has an atmosphere of nitrogen and oxygen because of the processes of life and death.
4. Differentiation in the early molten Earth caused heavier elements like iron to sink while the lighter elements and rocks stayed on the surface.
5. Tides on the Earth have slowed its rotation.
6. At the present time the main heat source for the Earth's core is radioactivity.

Thank you all! They were all true. :)

Answer 1

All are true, but 1, thought true, has some issues.

1. The Moon lost its atmosphere because of its low gravity.

The moon may never have had a significant atmosphere to lose. The sun may have blown it away as fast as it was created. But given that similar sized objects in the outer solar system -- jupiter and saturn moons and pluto -- have atmospheres, your book probably wants 1 to be true

2. The We think the Earth and Moon are both about 4.6 billion years old.

Yes. [Edit: Tham153, below, has a good point. Our current best theory is the Earth formed first, was run into by a Mars size object which merged with earth and threw a lot of debris into orbit. The debris coallased into the moon. You could say that they formed together after the collision, since the moon was formed out of Earth debris, or you could say a proto Earth formed first ]


3. The Earth has an atmosphere of nitrogen and oxygen because of the processes of life and death.

Yes, Oxygen is a byproduct of life. Otherwise our atmosphere would primarily be CO2 with some nitrogen

4. Differentiation in the early molten Earth caused heavier elements like iron to sink while the lighter elements and rocks stayed on the surface.

Yes, it is called the Iron Catastrophe. You should be able to google it.

5. Tides on the Earth have slowed its rotation.

Yes, and the same tides have caused the moon to orbit farther from the earth.

6. At the present time the main heat source for the Earth's core is radioactivity

Yes, but there is still a lot of residual heat from the "iron catastrophe," above. But that is just residual heat. It is old heat that has been there for billions of years. There is no present source for heat except radioactivity. This is a tricky question because it is ambiguous.

Answer 2

1. The Moon lost its atmosphere because of its low gravity.
True
2. The We think the Earth and Moon are both about 4.6 billion years old.
True
3. The Earth has an atmosphere of nitrogen and oxygen because of the processes of life and death.
True
4. Differentiation in the early molten Earth caused heavier elements like iron to sink while the lighter elements and rocks stayed on the surface.
Probably true?
5. Tides on the Earth have slowed its rotation.
False
6. At the present time the main heat source for the Earth's core is radioactivity.
False

Answer 3

1. It is difficult to say if the Moon ever had a true atmosphere. It may have had gas from outgassing when it was still active. However, its gravity does not allow it to retain anything except the heavier gasses (like Xenon).

2. Yes. There are various theories on how the Moon formed, but the serious ones agree on the age.

3. The Oxygen part is a 'pollutant' that was released by the very early plant life.

4. Yes. It is still going on. The sinking of heavier elements causes heating through loss of gravitational energy.

5. In 300 million years, the 'day' will last 26 of our present hours. The Moon raises a bulge in the Oceans, and this bulge causes the braking through friction over shallower areas (like the Irish Sea).

6. There are four sources of geological heat:
Lunar tides (the braking releases heat).
Gravitational loss as heavy elements sink (earthquakes release heat through this same mechanism)
Radioactivity
Magnetic dynamo.

The total is 13.2 TW (TeraWatts) of which 1.1 TW comes from the tides. I had found this out when doing a presentation nine years ago. I did not find out the proportion for each of the other three, so I do not know which is the "main" one.

Answer 4

1. Never had an atmosphere.
2. 4.6 million years is about right.
3. The atmosphere when life apparently began had oxygen and a big amount of hydrogen. Eventually most of the hydrogen bled off into space.
4. Yes.
5. Quite possibly. Like a large vessel of water on the top of sky scrapers prevents too much movement in winds.
6. Absolutely not.

Answer 5

I would say they are all true.

Update on #6:

There seems to be a lot of questions on the validity of question 6, but I stick to my guns. I believe it to be true. From a study done at UC Berkeley:

Radioactive potassium, uranium and thorium are thought to be the three main sources of heat in the Earth's interior, aside from that generated by the formation of the planet. Together, the heat keeps the mantle actively churning and the core generating a protective magnetic field.

The Earth is thought to have formed from the collision of many rocky asteroids, perhaps hundreds of kilometers in diameter, in the early solar system. As the proto-Earth gradually bulked up, continuing asteroid collisions and gravitational collapse kept the planet molten. Heavier elements – in particular iron - would have sunk to the core in 10 to 100 million years' time, carrying with it other elements that bind to iron.

Gradually, however, the Earth would have cooled off and become a dead rocky globe with a cold iron ball at the core if not for the continued release of heat by the decay of radioactive elements like potassium-40, uranium-238 and thorium-232, which have half-lives of 1.25 billion, 4 billion and 14 billion years, respectively. About one in every thousand potassium atoms is radioactive.

Answer 6

#2 is definately true.
also, the moon is moving away from the earth at a rate of 1/4 of an inch per year.

Answer 7

I don't think that anything is true about the Earth and the Moon; they are both figments of our imagination.

Answer 8

Well, idk about any of them except #2. What you hear about the earth being billions of years old is just a myth/rumor. It is actually 6000 years old at the most.
Scientists like to guess wild things and state that they're true. So technically the answer is actually yes, that people do think that, but in reality, it's not true.

Answer 9

i like agree with Simbaholic, the Earth is only about 6000 years old, maybe less and all those things, like 'fossils' and 'carbon dating' (I certainly wouldn't date carbon! just shows you how desperate nerdy types are! tee hee!) and 'radioactivity' (is that like when Britney is on three songs in a row?) are just stuff the guys (who can't get a date) made up.

Answer 10

1. False
2. True and False
3. True/False
4. True/False
5. False
6. False