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You are correct. The two forces are in opposite directions and cancel each other. Force is a vector quantity. When adding vectors the directions are as important as the magnitudes. Perhaps you are confusing gravitational field strength $g=GM/r^2$ and gravitational potential $V=-GM/r$. The former is gravitational force per unit mass, so like force it is a ...

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Let's take a look at how a planet is defined. According to IAU, it is a celestial body which: is in orbit around the Sun, has sufficient mass to assume hydrostatic equilibrium (a nearly round shape), and has "cleared the neighborhood" around its orbit. (IAU definition of planet on Wikipedia and the original Press Release by the IAU) As you can ...

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When rising in a gravitational field, a photon loses energy and frequency, but not speed. This relates to the idea that a distant observer would say that time appears to run slower deep on a strong field. If there were some way to observe the motion of a photon from a great distance, such an observer would say that a photon deep in a field was moving ...

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What you mean by "speed" is subtle in general relativity when comparing two disparate points. But, there are definitely a few facts that are universally agreed: Any observer sufficiently "close" to the light ray will always measure its local speed as $c$ The light ray, far from an isolated black hole, will always have velocity $c$ long after it ...

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