Is Earth Kind Of Like The Moon's Moon?

Question

When you're standing on the moon, looking up at the sky, can you see Earth? Does it appear in the same general place as the moon does on Earth?

In other words, instead of seeing a white cratery moon, do you see a blue/white/green planet?

Okay [sigh] I guess I'm not being clear. Bullet points:

-you are on the moon
-you are on the moon, looking at the sky
-you are on the moon, looking at the sky from the moon's perspective
-do you see Earth floating up there somewhere?

Wow I feel stupid now.

Answer 1

You can see pictures of the earth taken from the moon.

When looking at the earth, like looking at the moon, you sometimes see a "full earth", a "cresent earth", etc. depending upon the moon's relation to the earth and the sun (i.e. are you looking at the side of the earth towards the sun, or the dark side of the earth, etc.).

The earth, in the moon's "sky" looks bigger than the moon looks in our sky. Well, it's the same distance and the earth is bigger.

Answer 2

Yes, when standing on the moon you can see the Earth. It's a whole lot bigger than the moon, though. Where you see it is entirely relative to where you are on the moon, and standing on the far side of the moon you'll never see the Earth, since the moon's rotation is exactly proportional to it's revolutions meaning the same side always facest he Earth.

As far as the Earth being the "moon's moon", technically they do orbit each other, however the definition of "satellite" is a body which orbits another body larger than itself. Since a "moon" by definition is a satellite of its planet, the Earth isn't a moon of the moon.

For more information you should go to the library and check out a few books on the solar system. Or you can get lost on wikipedia for a few hours reading about planets and moons and the like.

Answer 3

q: If we were sitting on the moon, does the Earth appear to move across the sky? My friends all claim that it does because they have seen the pictures of earthrise from the Moon. I say that it does not move or moves very little, and that because we on Earth always see the same face of the Moon that the Earth does not appear to move across the sky from the Moon. (Josh Roberts, Washington, DC)

a: You'll be pleased to know that you are correct! An observer on the Moon will see the Earth move slightly in the sky, but it will always stay within a few degrees of the same spot. The photos of earthrise your friends mention are, I suspect, the ones taken from Apollo command modules orbiting the moon as they emerged from the lunar farside.


q: I believe you've made an error in one of the responses above. If one were sitting on the moon, looking toward the earth, it would be apparent tht the earth does not "stand still" with respect to the background stars. I'm fairly sure that the earth would wheel through the heavens with a periodicity equal to one synodic period, about 29.5 days. Not very fast, but certainly not staying within a few degrees of some fixed spot. (Johnie Spruiell, Southlake, Texas)

a: Celestial mechanics is not always intuitive, and I certainly do make mistakes, but on this occasion I stand by my answer. Lets tackle the problem in parts...

Imagine a line in space connecting the centre of the Earth with the centre of the Moon. During a period of about 24h, as the Earth rotated, the point where the line intersected the Earth's surface would describe a great circle crossing the equator twice and tilted a bit. Someone standing on that circle would see the Moon apparently passing overhead roughly once a day. In fact as the Earth rotates every 24h, the Moon revolves around it every 27 days - the sidereal month - so the intersection would actually take 24h 49m to return to the same spot.

The story on the Moon is different, though. It has captured rotation, so it spins on its axis with a period of 27d, exactly the same as the sidereal month. From the Earth we always see the same face of the Moon, and the centre-to-centre line would intersect the Moon's surface somewhere in the area of the Sinus Medii (selenographic latitude 0 and longitude 0)... always! Someone stood in this area would see the Earth directly overhead, the only variations being small periodic ones due to libration.

However, the patient observer on the Moon would indeed see something wheel through the heavens with a periodicity equal to one synodic period: the Sun. The combination of the Earth's 365 day journey around the Sun and the Moon's 27 day trip around the Earth produces a lunar day equal to 29.5 Earth days. Lunar noon in the Sinus Medii is essentially the same as the full moon seen from Earth, and the 29.5 period between lunar noons is the same thing as the synodic month from one full moon to the next.

Answer 4

The moon is a satellite of Earth. On the surface of the moon, the Earth appears to go through phases the same way the moon does on Earth. The Earth appears to be much larger.

Answer 5

Earth would appear much much....much bigger than the moon in the moon's sky. And the moon does not rotate, so the position of Earth would be the same throughout it's rising and setting cycles.

And to the guy above me....the Earth doesn't provide light either......only the sun does that.

Answer 6

You can see the earth from the moon, but the proportions are different. The earth is about 6 times the size of the moon I think. Also, remember that moon orbits the earth, the earth does not orbit the moon.

Answer 7

No, because the moon goes around earth, making it a moon. Earth is kind of like a moon to the sun though.

Answer 8

It's dark on the moon. Always. But, there is even the darker side of the moon which is always the dark. No growth. Yes, you can see the earth when you look up. But the moon rotates around the earth so it depends on where you are if you can see the earth or not.

Answer 9

Only one side of the moon faces Earth. Depending on where you are standing on the moon, the Earth is either in one spot or not visible.
Lalana is all wrong about the dark side of the moon. There is no dark side, only a side that always faces away from Earth.

Answer 10

The moon doesn't have a moon of it's own...but...

Yes...

The earth is a big blue jewel in the moon's sky...but remember...the moon doesn't rotate on it's axis...so its days are two weeks long, because it completes one rotation around our planet in 4 weeks...so the Earth rises and falls on the moon every two weeks...