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aj gokhale
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How can inhabitants of the far side of moon guess that the moon is revolving around the earth?
Hi Van:Vanadium 50 said:Buzz's reply is full of irrelevancies.
aj gokhale said:How can inhabitants of the far side of moon guess that the moon is revolving around the earth?
Hi Van:Vanadium 50 said:But the Earth is visible on almost 20% of the far side.
But they still don't know what they are rotating around. and as buzz did ... that is the way I also interpret the OP questionChronos said:Irrelevant, they still see they rotate wrt the sun and see other planets in the solar system doing the same thing.
aj gokhale said:How can inhabitants of the far side of moon guess that the moon is revolving around the earth?
Bandersnatch said:I'd measure 'daily' parallax of visible planets.
Providing the distances to those planets are known with some accuracy (found out e.g. by using yearly parallax measurements), it will also net the observers an estimate of the mass of the planet they're orbiting.
Hi Bandersnatch:Bandersnatch said:Providing the distances to those planets are known with some accuracy (found out e.g. by using yearly parallax measurements), it will also net the observers an estimate of the mass of the planet they're orbiting.
You're right. This is assuming the observers do know what is the radius of their orbit around the Sun, so that they can use yearly parallax at all.Buzz Bloom said:I may be mistaken about this, but I have a vague memory of reading that it took astronomer a rather long time after knowing the relative distances between the various objects (sun, planets, moons) to get a reasonably accurate distance scale for these measurements. As I recollect, radar echos from the moon nailed it down.
I took the question to mean that we are actively trying to find if there's a planet we're orbiting, so we'd set out to surmount just those kind of obstacles. I.e., make a working hypothesis that there isn't one, and try to disprove it by checking whether all parallactic measurements are consistent with no additional orbital motion.Janus said:The above problems are not insurmountable for someone dedicated to making them, its just that they are not the types of observations that would likely to be made if you weren't already looking for it.
Inhabitants of the moon can determine the length of their revolution by observing the phases of the Earth. Just like how we see the moon's phases change over the course of a month, the lunar inhabitants can see the phases of the Earth change over the course of their revolution.
Yes, the inhabitants of the moon can use the stars to track their revolution. Just like how we use constellations to navigate on Earth, the lunar inhabitants can use the stars to determine their position in relation to the Earth and track their revolution.
Lunar inhabitants can measure the length of their revolution by observing the Earth's position and movement in relation to the stars. By tracking the Earth's position in the night sky, they can determine how long it takes for the Earth to complete one revolution around the moon.
Yes, the length of the revolution may vary slightly for inhabitants living in different parts of the moon. This is because the moon's orbit around the Earth is slightly elliptical, causing variations in the distance between the moon and Earth.
Lunar inhabitants can use technology such as telescopes and satellites to track their revolution. By measuring the distance between the Earth and moon at specific points in the revolution, they can calculate the length of their revolution and make more accurate predictions for the future.