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2 votes

Is it possible to achieve a stable "selenostationary" orbit around the Moon?

All of the other answers in this thread are completely correct, however I think there's a point missed by focusing only on the Moon-Earth system. Any tidally locked moon will always have its ...
user267545's user avatar
3 votes

The consequences and the mechanisms of a shift of the Earth away from the sun

Your idea of a planetary-mass black hole is on track. The real challenge here is that the black hole only gets one chance to change the orbit as it passes through the solar system. It would definitely ...
Mark Foskey's user avatar
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4 votes

Celestial "orbits"

The model of the elliptical orbit is a close approximation of the reality—and even Kepler knew that, when he wrote that “orbits are ellipses.” In reality, gravitational interactions between the Sun, ...
Pierre Paquette's user avatar
5 votes
Accepted

Do the Galilean moons' orbits around the Sun have loops (i.e. have concave parts)? And if so, how can their orbits be graphed?

Compare the orbital speeds and use the superposition. Jupiter's orbital speed around the sun is around 13km/s. Io's speed around Jupiter is around 17km/s. So it will actually go backwards. For ...
planetmaker's user avatar
  • 17.7k
6 votes

Celestial "orbits"

You are right. But you miss a few quirks of reality, or some fine-print of the applicable physics. Yes, the Moon is moving away from Earth as slowing down Earth's spin rotation means that angular ...
planetmaker's user avatar
  • 17.7k
9 votes
Accepted

Celestial "orbits"

Physical theories describe how things change in given circumstances (if the theory is right). In practice this means that they are applied in simplified ways, where the simplifications of ...
Anders Sandberg's user avatar
-2 votes

Are there naked eye binary stars with periods less than 100,000 years?

Yes, Algol is not far away. The two stars orbit each other in 2.867328 days. Further examples.
9herbert9's user avatar
5 votes

Are there naked eye binary stars with periods less than 100,000 years?

I queried the 4th Catalog of Orbits of Visual Binary Stars for systems with both components having $V<6$ and period $<10^5$ years. There were 77 examples, but the widest separation is 17.5 ...
ProfRob's user avatar
  • 146k
5 votes

Is an earth-sized moon orbiting a super-earth feasible?

This is an answer only to the second part of your question. If such an enormous moon somehow gets formed or captured, its tidal interaction with its host planet will follow the regular laws. If the ...
Michael_1812's user avatar
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