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

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If planet like Jupiter is massive enough to hold hydrogen with its gravity is it bound to become a star?

I have been reading about Jupiter as of late and reason I am asking is if Jupiter has strong enough gravity to pull hydrogen to itself then it should be only matter of time when it will acquire enough ...
13
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2answers
1k views

What would be the rate of acceleration from gravity in a hollow sphere?

Lets say the Earth is hollow and you are in the center of it (Same mass except all of it is on the outside like a beach ball) If you move slightly to one side now your distance is closer to that side ...
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1answer
70 views

Drift of Earth's orbit?

How much has Earth drifted (inwards or outwards) from its orbit about the sun? Or has Earth has not moved at all, compared to, say, 1000 years ago? 10,000 years ago?
3
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1answer
33 views

Protoplanet formation & Kessler Syndrome

In the early stages of the solarsystem rocks clumped together randomly until their gravity drew in more material which led to protoplanet formation. But how does the dust and do the rocks form bigger ...
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1answer
36 views

If I observe a planet because of reflected sun-light, how does the radiant flux vary with distance?

I wish to figure out how the flux of the sun's reflected light from a planet varies with distance, so assume an observer is on the sun, looking at a planet, and the light originating from the planet ...
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2answers
29 views

Planet Sized Generator

I have an interesting idea for an energy generator and I want to see what you think. Basically, you take a small planet and drill from one side to the other so it looks like a sphere intersected ...
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2answers
49 views

Do the outer gas planets radiate their mass?

We know that the sun experiences angular momentum loss, and radiates a portion of it's mass (though helicity is conserved). Can we say the same about massive Jupiter, or even Saturn, Uranus or ...
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5answers
2k views

What would happen if I were to fall into a massive hollow planet?

Imagine, if you will, there exists somewhere out there a supermassive planet. For some reason, this planet is only a shell of its former existence and all that is left is a crust of substantial size ...
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0answers
42 views

Could there be a dark matter planet? [duplicate]

Since dark matter is gravitationally "charged", by which I mean it has mass and attracts things, could it bunch together to form a planet?
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0answers
13 views

Saturn's Hexagon [duplicate]

I am currently trying to understand the formation or indeed the explanation as to why the hexagonal north polar vortex on Saturn is exactly that: Hexagonal. I understand that the most prominent ...
0
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1answer
49 views

Why Earth is not a cuboid? [duplicate]

There must be some scientific reasons for why earth is a spheroid but what are they? If Earth would be a cuboid, Would it matter?
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3answers
110 views

Is the planet Mesklin as described in Hal Clement's Mission of Gravity correct?

The book Mission of Gravity describes a planet with a mass of 16 times Jupiter spinning at a rate of one revolution every 17.75 minutes. This causes it to stretch out into an oblate spheroid and has ...
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3answers
92 views

Why is Earth's gravitational pull only at its center?

Why is Earth's gravitational pull only at its center? Does acceleration due to gravity remain constant wherever I go in and on the Earth?
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1answer
32 views

How do we find the cone angles of the conic sections that are the Newtonian orbits?

In planetary motion, when the eccentricity of a conic section and its semi-latus rectum are known, how do we find out the cone's semi-vertical angle and angle of cutting of the cone by plane?
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2answers
94 views

Are there any solar systems without a sun?

1) Are we able to study any other solar systems, that once contained a sun the size of our own... that has since died, or gone Red Giant, the way it is predicted our sun will die? 2) If we have been ...
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0answers
74 views

Variation on the “Hole through the Earth” problem

In the news recently was the announcement that the answer to the classic Newtonian mechanics question of the time it takes for a body to fall all the way through the Earth was corrected to account for ...
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0answers
43 views

How much water is needed for Saturn to float in?

Saturn floats because it's density is less than that of water. Just how much water would be needed? Assume a cuboid tank holding it. And when we actually put saturn in that water, how far in the ...
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0answers
30 views

Why isn't $g$ larger on the equator? [duplicate]

I understand that at the equator, you will have maximum centripetal force acting on you, whereas if you're standing directly on the pole you will have none. But because centripetal is a resultant ...
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1answer
92 views

Largest size of a low gravity, Earth-like planet with Volcanoes and Earthquakes?

Provided that the Solar System consists only of Sol, a planet, and the planet's moon.... How large can my planet be so that it has low enough gravity that teenage human girls trained for jumping, are ...
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2answers
65 views

Is it possible for a planet to be “axially locked”?

What I mean is, can a planet orbiting its sun have a fixed rotational axis relative to the sun ie in the case of earth the tilt is like this /........(sun)......./. as it goes around the sun. ...
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2answers
70 views

What should we do If we wanted to increase the angular velocity of a planet? [duplicate]

We could hit it with really fast objects, but could we manipulate the orbit of a large satellite to speed up its rotation? What would be the easiest way?
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0answers
39 views

Explaining why planets are round [duplicate]

is it possible to prove that planets (and/or stars) are always round (elliptical if you consider the spin)? Is there a set of equation that demonstrate that fluids (after all, molten rocks "floating" ...
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1answer
22 views

Inclination of planets

What is the inclination of each planet with the equator of the Sun? Doesn't this have a relationship with the eccentricity of the planet's orbit?
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1answer
84 views

Does spacetime have symmetric curvature around an object? If yes, then why do planets revolve around the Sun in elliptical orbits?

Does spacetime have symmetric curvature around an object? If yes, then why do planets revolve around the Sun in elliptical (as opposed to circular) orbits?
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1answer
47 views

The stronger the gravity, the faster an object will fall? [closed]

On a planet with gravitation ten times stronger than that of Earth's, will an object fall faster? Let's suppose that there are two planets; Roddo and Earth, respectively. Roddo has ten times the ...
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3answers
87 views
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1answer
61 views

How do you calculate density if you also account for gravity?

Consider this. I have an Earth-sized quantity of water that I throw into space. Naturally, it will assume the shape of a ball. Now hear me out. Density's definition generally assumes that it will ...
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1answer
80 views

How does the Earth rotate, given that the torque acting on it while revolving is zero?

I've come to understand that the torque acting on the Earth while revolving the Earth is zero. Torque is the force responsible for rotation of a body. So how does the Earth rotate?
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1answer
72 views

How dense and compact would Kepler-5b need to be to become a black hole

How dense and compact does Kepler-5b need to be to become a black hole ?
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6answers
4k views

If the gravity at the center of the Earth is zero, why are heavy elements like iron there?

If gravity is zero at the center of the earth, why is there a core of heavy elements, such as iron? Alternate question for the opposite hypothesis: If gravity is greatest at the center of the ...
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2answers
1k views

How can a gas giant be about the same size but six times more massive than Jupiter?

I've just read this article: http://www.sci-news.com/astronomy/science-kepler-432b-new-super-jupiter-exoplanet-02490.html And I wondered how this could be possible? Maybe it's because this gas giant ...
7
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2answers
104 views

Why aren't there any clear planets/ stars?

Most gases are clear. So why are there not any planets or stars that are more or less clear in color? I suspect this question may be extremely stupid.
2
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3answers
160 views

Could the sky on a planet theoretically be any color?

The sky on the Earth is blue. Could the color of the sky on a planet with an atmosphere be of any color theoretically? Which colors are the most likely? I think it would be really awesome to have ...
2
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2answers
193 views

Infinity problem: Why is gravity $g=0$ zero at the center of Earth if according to Newton gravity formula $g=GM/R^2$? [duplicate]

It is said that value of $g=0$ at the centre of the Earth. $g$ is calculated using the formula $$ g=G*M/R^2.$$ When $R = 0$, $g$ approaches infinity. I have two ...
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1answer
50 views

Why does a parachute open up faster on Mars than on Earth? [closed]

I recently heard that a parachute opens up much faster on Mars than on Earth. Why is that the case? More specifically, during a NASA Edge TV program, one of the scientists working on parachute tests ...
2
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1answer
37 views

Calculating the size of exoplanets with moons

When astronomers detect an exoplanet using its transit and calculate its size to be, say twice the earths size, do they have any way of knowing that its actually not a slightly smaller planet with a ...
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2answers
170 views

Why are planets in unstable equilibrium in a stable orbit

It is well known that a planet in stable orbit is in unstable equilibrium. If e.g. the moon was just a few m/s slower in velocity, or a few m closer to the earth than it is, the gravity would ...
0
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1answer
44 views

Are the large moons of Jupiter, Saturn, and Neptune still cooling and does this give and indication of their age?

The core temperatures and the rate at which they emanate heat should correspond to their estimated age. Other forces may create some heat such as the tidal locking that is supposed to be the source of ...
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0answers
44 views

Finding the temperature of Earth from temperature of Mars and its distance from Sun [closed]

I am to compute the temperature of planet--in fact I've already found out it's Earth--knowing only: the surface temperature of Mars (210 K) and its distance from Sun (1.524 AU) and of course ...
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2answers
65 views

A Chevy Silverado on Mars [closed]

Another topic that no one seems to consider is driving a 4x4 truck across the surface of Mars, years of experimenting with a robot vehicle when you have 100 years of progress with the motorcar. So ...
3
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2answers
71 views

Physics of tidal locking: can the process be underdamped?

Is it possible for a satellite undergoing the process to overshoot the required rotation rate for tidal locking? For example, if its rotation rate is being slowed, can it become slower than it needs ...
2
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0answers
65 views

Protoplanetary disks, angular momentum and prograde orbits

So you've got a protoplanetary disk and you're going to gravitate yourself some planets together. The disk is made up of the usual planetary system stuff, dust and gas and whatnot, orbiting a common ...
1
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1answer
50 views

How have the duration of the martian day changed in the past?

There is a panspermia theory which claims that life might have begun on Mars and I currently read a post that the human circadian rhythm is closer to the martian day length (about 25h) than the day ...
1
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1answer
147 views

Could this planetary superalignment happen?

Here's the 'superalignment' I'm referring to: We've all heard the stories about 'mystical planetary alignments' that will increase/decrease the effective surface gravity experienced on Earth (one ...
6
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3answers
825 views

Does the Earth actually rotate around the sun? [duplicate]

Why does one say that the Earth rotates around the sun? There should be no preferred reference frame and from an observer on the sun, the sun will rotate around the Earth.
0
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1answer
57 views

How do I calculate the right ascension of the points along the ecliptic at given elevations?

How do I calculate the right ascension of the point along the ecliptic nearest the sun at sunset and sunrise that is at a given altitude/elevation? For example, I'd like to compute the right ...
0
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2answers
51 views

Angular Momentum conservation in star system

This question is related to what happens to a planetary body(like earth) when the star it is orbiting collapses under its own gravity. Suppose a star is rotating about its axis with some angular ...
5
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1answer
91 views

Gravity on and inside a planet-sized bi-lobed body

Admittedly, for yet another science-fiction project Say I have a planet-like body shaped like a sphere with a torus subtracted out of it, leaving a sort of "apple core" shape. Firstly, is the ...
2
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1answer
85 views

Tidal locking of a planet to a satellite

As in the case of Pluto and its moon Charon, both the bodies are tidally locked to each other, will the Earth ever be tidally locked to the Moon? Is there any effect on the rotation of the Earth ...
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2answers
95 views

Initial Velocity For Orbital (Gravity) Slingshot At Hit Moving Target

In this problem we have three masses, Mass A is on the left side of the sun Mass B is the sun, and Mass C is on the right side of the sun. I want to calculate the initial velocity of Mass A to hit ...