# Science Question (Scifi Story)



## LMThomas (Jun 19, 2014)

If you were standing on the surface of a moon, approximately the size of the earth, orbiting a planet approximately ten times the size of the earth, what would you daytime, night sky look like?  

How big would the planet that you were orbiting appear in the sky?  

Would it be bigger than the star the planet orbits (assuming the planet is the same distance from the star as earth is, and the star is a similar size to the sun)?  

Assuming the moon is tidally locked to the planet, would the planet appear to move in the sky, or would it always be in the same position?  

Would stars be visible at night?

Thanks, guys.


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## movieman (Jun 19, 2014)

LMThomas said:


> How big would the planet that you were orbiting appear in the sky?



Depends on how far away it is.



> Would it be bigger than the star the planet orbits (assuming the planet is the same distance from the star as earth is, and the star is a similar size to the sun)?



Depends on how far away it is.



> Assuming the moon is tidally locked to the planet, would the planet appear to move in the sky, or would it always be in the same position?



The Moon wobbles, so the Earth appears to move a few degrees in the sky as the Moon orbits it. This case would probably be the same, as a perfect lock is unlikely to happen. For example, the sun affects the Moon's orbit as well as the Earth.



> Would stars be visible at night?



Depends on how far away the planet is, and how reflective. At night you'd always see at least part of the sunlit side of the planet, so if it fills a large fraction of the sky and is covered in ice, it might be so bright that you wouldn't be able to see the stars.

Note that you can't get too close, or the gravitational tides would pull the moon apart. Look up Roche Limit for details.


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## qwertyportne (Jun 28, 2014)

That's an interesting question. First thing came to mind was the astronauts jumping around our moon because the gravitational forces were less than here on Earth. Good answers Movieman. LM Thomas, are you planning a sci-fi story? Sounds like it could be a good one. Let us know when you post a chapter. Or will it be a short story?


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