Celestial body that orbits following an elliptical path around a star or stellar remnant.

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Are the orientations of spin-axes and binary/planetary orbits random or is there any relationship with the Galactic plane?

In an answer to another question, a claim has been made that orbit/spin orientations are random (at least within our own Galaxy), except perhaps towards the Galactic centre. I have dabbled in this ...
5
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99 views

What coordinate system is used to describe planets positions in the universe?

How are planets positions described in the space and in respect to what? For example is Sun the origo and right now at this moment Earth has [coord_X, coord_Y, coord_Z]? or maybe [lng, lat]? ...
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142 views

Hemispheric dichotomy of Mars and unstable spin axis

Is the following explanation plausible? Can you spot any flaws? Mars doesn't have a large moon to stabilise its axis of rotation. At some point early in its formation its axis might have been ...
4
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66 views

Are there certain alignments in planetary orbits that create interesting effects in the moons or planets?

We have some interesting examples such as Mercury's perihelion The planet Mercury is especially susceptible to Jupiter's influence because of a small celestial coincidence: Mercury's perihelion, ...
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102 views

Only gravitation and Newton's $2^{\mathrm{nd}}$ law needed to derive Kepler's laws?

It is known that Kepler's laws of planetary motion can be derived from Newton's laws of motion and his law of universal gravitation. However, are all of Newton's laws of motion necessary? According ...
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How did the radiative flux of each gas giant planet change with respect to time (since their formation)?

We know that each gas giant planet was warmest when it was young. This warmth came from internal heating from both radioactive decay and from gravitational potential energy. This warmth, in turn, ...
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58 views

What would the collision between a (large) solid planet and a gas giant be like?

Assuming a Jupiter-like planet and an Earth-like planet (Except, say... half the mass of Jupiter), what would happen when the two collide? For clarification: What would the actual collision be like? ...
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48 views

What speed should have an alone planet to have a habitable zone due to relic radiation?

What speed should have an alone planet to have a habitable zone due to relic radiation, without any star involvement? How much time the planet will be able to remain in the habitable zone before the ...
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55 views

Stable planetary rotation states

In reading an article about theories as to how the slow retrograde rotation of Venus may have come into being, the article Why Venus Spins the Wrong Way (Franzen, 2001) stated that it is bound to ...
2
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277 views

For two planets in a 2:1 mean motion resonance , where will their periastron and apastron points be?

I want to animate the changing orbits of planets when they enter a mean motion resonance. Using a 2:1 resonance, I want to show a low-mass inner planet and a low-mass outer planet being tugged by a ...
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462 views

How do I find equations for the distance of the planets relative to one another?

I know I should be able to piece together some basic Newtonian equations for this, but I'm not sure where to start. I want to be able to choose one planet as the center and calculate its distance ...
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62 views

Sedna, VP113 and the likelihood of the PX/Tyche/Thelistos hypotheses

The recent discoveries in exoplanetary science (specially those findings of planets orbiting far far away from its parent star/stars) raise questions about how much we know about the (true, AIU ...
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45 views

How strong can tidal forces get?

I am imagining a planet the size of Earth being in close proximity to something of high mass such as a gas giant or a star, but ultimately I'd be more interested in how to figure this out myself. So ...
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47 views

Could there be a planet just as the Earth, but bigger?

Could there be a planet twice or thrice the size of Earth but while being the same? and by the same I mean, hosting the same life as Earth, having a day last 24 hours and a year 365 days. Basically, ...
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21 views

What are the practical limits on the pecular motion of stars?

What are the practical limits on the pecular motion of stars and planets?