# Tag Info

27

You are correct. The Earth would always appear in approximately the same location in the sky, when viewed from a point on the lunar surface. And it would be seen to spin, the continents coming in and out of view over the course of an Earth day (24 hours). The sun would make it's way across the sky, from one horizon to the other over a period of about two ...

14

To add to Mark Bailey's answer; the Earth would indeed hang in the sky and rotate, but it would also wax and wane over the course of a lunar day (27.3 Earth-days). Starting at lunar dawn, the Earth would be half-full. The Earth would then wane (more shadow) towards lunar noon. At lunar noon, the Earth would be all in shadow (New Earth) and quite close to ...

11

Still new at stellarium but here are some quick capture gif lasting one month. Sorry about the quality- limited to 256 colors for smaller gifs. Date on lower left corner. By the way the sun is of course the brightest and i use it as reference for recording (start record when sun is in frame then stop when it appears again in the same position which is ...

7

It's highly doubtful you could see any normal light source on the surface of the earth. Using $$\text{brightness} = \frac{\text{luminosity}}{4 \pi \times \text{distance}^2}$$ (with brightness in watts, and luminosity in watts per square meter. and distance to moon of $3.84 \times 10^8$ meters.) Try a hypothetical light source 100 megawatts output, all ...

6

The dark parts of the Moon are lightened up by "Earthshine". That is sunlight which is reflected from Earth to the Moon. Just like the ground on Earth is lit up a bit by the Moon at night, so is the ground on the Moon lit up a bit by the Earth in the lunar night. And even more so because Earth is much larger in the lunar sky, than is the Moon in our sky. And ...

5

As HDE 226868 noted in his answer, the Sun is not going to go supernova. That's something only large stars experience at the end of their main sequence life. Our Sun is a dwarf star. It's not big enough to do that. It will instead expand to be a red giant when it burns out the hydrogen at the very core of the Sun. It will continue burning hydrogen as a red ...

4

To expand a little more, yes the Earth would hang in the same spot in the sky, moving around in a small circle as the moon rotated around it over the course of each of its 28 day orbits. It would have phases, full Earth when the moon is between it and the sun, new Earth when the Earth is between the moon and the sun, and wax and wane between these two ...

3

Is there any resource that provides these current values? Yes. The JPL HORIZONS on-line solar system data and ephemeris computation service provides these values, and much more.

3

What a nightmare - there is no accepted definition. A common method is to use the fraction of the night (between the times of astronomical twilight) that the moon spends above the horizon. The problem is that this does not correlate perfectly with fractional lunar illumination or sky brightness. It does provide a good method of deciding when a night is ...

2

Yes, the Earth would be visible even during day on the Moon. Without a (significant) atmosphere diffusing light, the day sky would be much like the night sky on Earth. If you were to look straight up such that you couldn't see the ground, you may not even notice that it was day at all (save for the Sun shining down at you). This could actually be rather ...

2

It's poetically called The Old Moon in the New Moon's Arms. Project Earthshine used measurements of the brightness of the non-sunlit portion of the moon to accurately determine earth's albedo: A global and absolutely calibrated albedo can be determined by measuring the amount of sunlight reflected from the Earth and, in turn, back to the Earth from the ...

1

It is called "Tidal locking", or "gravitational locking" or "captured rotation". According the the Wikipedia page on "tidal locking" (check the references for sources), it is due to Earth's gravity causing a small tidal bulge on the Moon, which affects its rotation. Over time, the Moon's rotation, affect by Earth's gravity, makes it's orbital rotation ...

Only top voted, non community-wiki answers of a minimum length are eligible