# Tag Info

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To have an orbit perpendicular to the ecliptic plane, it would need to have an inclination of exactly 90 degrees. Orbits with inclination less than 90 degrees are prograde, and with greater are retrograde. Asteroids with inclinations even close to perpendicular to the ecliptic are rare since: Most of the matter rotating around the Sun coalesced in the ...

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Consider a particle with mass m, orbiting in a circle a body with mass M. The gravitational force must be the centripetal force causing circular motion, so $$\frac{GMm}{r^2} = \frac{mv^2}{r}$$ Cancelling the $m$ and $r$ and square rooting gives: $$\frac{\sqrt{GM}}{\sqrt{r}} = v$$ So you see the velocity is inversely proportional to the square root of ...

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Mercury is tidally locked; it has a 3:2 resonance with the Sun, where it rotates three times for every two orbits. It is well understood that Mercury is tidally locked, but modern explanations for how it could’ve come to be are currently unsatisfactory (see this publication from Nature https://www.nature.com/articles/nature02609). It will probably never ...

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The rotation of our Milky Way in general is derived from observations of the kinematics of gas and stars throughout our galaxy. See for instance a recent compilation of Milky Way rotation curve data from which this figure is taken The rotation curve of the Milky Way as derived from gas kinematics (blue), star kinematics (orange) and masers (black).

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Here is an example of what is asked for, or something very similar: The Saturnian moons Janus and Epimetheus share their orbits, the difference in semi-major axes being less than either's mean diameter. This means the moon with the smaller semi-major axis will slowly catch up with the other. As it does this, the moons gravitationally tug at each other, ...

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