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Questions tagged [planets]

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

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1answer
551 views

Why do planets have different rotational periods?

We all know that the solar system was formed from a nebula of gas and dust. But why is it that the earth has a period of 24 hours to rotate on its axis and why does the sun take 27 days to complete a ...
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Does the spinning of a planet effects the attractions on other planets?

Imagine we have two planets spinning very fast around their axis, lets say ones in every minute (both with the size of the Earth). When they are at a distance will they get faster, slower or perhaps ...
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Did moon gravitational force pulled metals and minerals higer?

Robert J. Sawyer's novel Illegal Alien states: A civilization living on a planet without a moon has much bigger trouble mining raw resources because moon's gravitational pull pulled materials ...
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Why is a point source (star) more twinkling than a disc source (planet)?

Most scintillation effects are caused by anomalous refraction caused by small-scale fluctuations in air density usually related to temperature gradients. Stars twinkle because they are so far from ...
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What determines how long a day is on a planet?

A quick Google search shows that the day is about 116 (Earth) days for Venus, 1 day for Mars, 10 hours for Jupiter. I can't find an obvious connection between how long a day is with anything. Is it ...
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1answer
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Nice model of Solar system: Does gravity produce larger distance between objects? [closed]

Counter intuitive it seems that in some cases gravity results in a higher orbit and greater distance. For example the moon is attracted to the Earth but because it gets a higher speed it ends up ...
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1answer
136 views

Why don't planets radiate in orbit like a charged particle? [duplicate]

According to Maxell's Electromagnetic Wave theory, an accelerating charged particle radiates energy and this is one of the arguments due to which the Rutherford model of an atom(In which Rutherford ...
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1answer
109 views

How do you calculate unified planetary precession incl. both GR and Newtonian contributions?

We know the theory of general relativity (GR) accounts for the illusive $43$ arc seconds of precession of the perihelion of Mercury. The calculation is well known and well studied. How does one ...
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1answer
82 views

Fusion inside a planet with high concentration of radioactive elements?

If an Earth-sized or larger planet had sufficiently large amounts of radium, thorium or uranium, couldn't the resulting fission trigger periodic fusion of hydrogen? I'm thinking of fission happening ...
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Mars' Moons and its Dynamo

Given we could move Mars' moons, Phobos and Deimos, closer to each other, such that the gravitational effect between Mars and its moons is similar to the effect that Earth and its moon have on each ...
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Is there a connection between the precession of Mercury's orbit and the speed of gravity (light)? [closed]

I once read an article (in the nr. 10 2005 issue of NW&T, a Dutch science magazine) in which a connection was made between the precession of Mercury's orbit and the speed of gravity. It was ...
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1answer
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Why are large planets away from the Sun and smaller planets near the Sun?

In school, we are taught that every planet attracts every other. $$F=G\frac{mM}{R^2}$$ Stars have a large gravitational force and it attracts every large object. Every planet has a different mass ...
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What would happen to an unprotected human body on the surface of Venus?

In the tremendous heat and pressure on the surface of Venus what would happen to an exposed human body? Would it burn up, dissolve, mummify or something else? Presumably the water and fats would boil ...
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How to determine the weight of an object in other planets?

I was curious about what my weight would be in different planets so I found myself on this site: https://www.exploratorium.edu/ronh/weight/ But while Neptune is about 17 times more massive than ...
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3answers
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Why does Earth rotate on a single axis?

You often see gymnasts flip and twist at the same time. They rotate on two axis. Earth twists, but doesn't flip. It only rotates on one axis. I'm not sure, but I think the same is true for all other ...
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Equation to predict the shape of a planet [duplicate]

I need help calculating gravity and shape of a planet based on a few factors. If a mass rotates quickly enough, the inertia (or "imaginary centrifugal force") will pull the mass outward "...
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1answer
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How long would it take Mars to lose its atmosphere if we gave it one?

I've read that one of the reasons Mars doesn't (any longer) have an atmosphere is that it loses more gas to the solar wind than the Earth does, because its core has solidified and it therefore lacks a ...
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If Earth spun faster, would I be able to jump higher? [duplicate]

I'm asking mostly in relation to the forces acting on a person, but it would also be nice to know if there would be any impact on muscle strength, similar to when an astronaut goes into space.
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1answer
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Would the Star Wars Death Star in a low Earth orbit be torn apart by Earth's gravity?

I got the question from this reddit comment: Well the moon is a quarter million miles from earth. The death star would only need to be in low earth orbit to stay aloft (which according to Wiki is ...
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Gravitational field strength to distance graph [duplicate]

Can someone please explain why the graph is linear from the start to the surface?
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1answer
652 views

Why some planets revolve around Sun in opposite direction than that of Earth? [closed]

Why some planets in universe revolve around sun in opposite direction of the direction in which earth revolve around sun? Please help me to find the answer of this question.
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3answers
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How to prove that Gravity happens in one plane?

How can we prove that an object which is orbiting another object by its gravity always moves in one plane in a full period? Not in different diffrent planes (two body system)
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1answer
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Shape of planetary orbits

What makes Venus' orbit almost circular, though mercury's is highly elliptical,even though it is closer to sun ? Further, Why is mercury's orbit most elliptical right after Pluto ?
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What is the value of the Riemann tensor at the center of Earth and why is it not 0?

I have read this: What is the general relativity explanation for why objects at the center of the Earth are weightless? And this: Gravitational time dilation at the earth's center And this: ...
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In a rocket, when is the Earth's gravitational field negligible?

The escape velocity on Earth is around 11km/s, and this is the speed required to escape Earth's gravitational field. However nothing would ever get far enough away to be completely free of it. At ...
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How can we explain Saturn's non-spherical shape in terms of forces? [duplicate]

As we know the Saturn's shape is not spherical. In fact, its polar radius is almost 10% smaller than equatorial radius. This flattening is caused by the rapid rotation of this planet. Image credit: ...
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Why the Moon does not change its orbit from Earth to an another planet?

I know that Earths gravity pulls down the Moon towards the Earths center and Moon is falling on Earth, but because of its change in velocity it never fall on Earth but orbits around Earth. Now I don'...
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If a planet's core is heated by its gravitational pressure, where does that energy come from?

I just saw a show about the theorized "Planet 9." One possibility is that it's an ice planet. But it could have a liquid water core from its gravitational energy crushing in the core and making it ...
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Gravity between Two Planets … (I have the Solution but it doesn't make sense … !)

So the Question is : Two Planets that Have the masses of m1=M,m2=9M , Both of the planets have the radius of r the planets are Set to 16r away form each other ... A. At what distance between the ...
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Why does Uranus not experience gyroscopic effect?

As I understand, gyroscopic effect is when a body has multiple distinct axes of rotation. This video shows this effect when a body already rotating in one axis is made to rotate another axis ...
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1answer
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Venusian days vs. Terrestrial days: Why the Big Difference in Length?

The diameters of Venus (7,520.8 miles) and Earth (7,917.5 miles) are comparable, but the disparity of the length of the day for each planet - as expressed in terrestrial hours - is enormous; a day on ...
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2answers
754 views

What is the unit of time “JD” in an astronomical context?

For my high school physics project I am required to research a planetary system. The orbital period of the planets are given in JD. What are these units? I've tried to research it, and I've found it ...
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What happens when a planet's core freezes?

We know the Earth's interior is differentially rotating -- the core is rotating much more quickly than the crust. This is possible because the outer core is liquid and is presumably low enough ...
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1answer
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Are there any planets without atmospheres? [closed]

Just after observing a cold response on my previous question i m asking this question in a completely different way(as my knowledge about atmospheres has developed). My question is that are there ...
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1answer
116 views

Gravitational potential of a nearly spherical body

In my book an equation is stated for the gravitational potential $V(r,\theta)$ of a nearly spherical body, such as the Earth. It says that the equation is derived using Laplace's equation though the ...
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1answer
841 views

Mathematically calculate if a Planet is in apparent Retrograde motion

I am trying to find out if a planet is in an apparent retrograde motion with respect to the earth at any given point in time. Given the time in Julian days. I already have the geocentric and ...
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Formation of planet

I was told that if we assume the formation of planet is due to the gathering/collapse of the cloud, we can use rotation period of a dust particle to determine if that particle will be attracted to the ...
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1answer
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Why is Venus cloud covered but not in an ice age?

I understand that Venus is closer to the Sun, but shouldn't Venus's cloud cover effect it in the same way as Earth's cloud cover would cause an ice age? Venus with no clouds.
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3answers
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Minimum distance for a natural satellite

Is there a minimum distance between a planet and its natural satellite that should be maintained so as to keep the satellite from crashing into the planet? Can someone explain me the physics behind ...
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1answer
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Is it possible to find the mass of a planet and its moon from only their diameter and the distance between them?

For example, a planet has a diameter of 200,000 km and its moon has a diameter of 20,000 km, the distance between them is 100,000 km. Would it be possible to find their masses?
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If Earth had rings?

If Earth had rings, would they center on the equator like Saturn's rings do on its equator?
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Relation between average density of planets and their distance from the sun

In this graph,I plotted the points as (Distance from the Sun,Average Density) of the planets.Distance of planets from the sun are in Astronomical units and the average density is $gram/cm^3$ I also ...
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1answer
461 views

Where to start, if I would like to run a planet climate simulation? [closed]

I would like to understand the math behind it, and maybe write an own climate simulator program. I know, that it is a really hard subject. But I'm curious, and I would like to learn more about it. But ...
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1answer
129 views

Why is the weight of a constant mass different on the poles and on the equator? [duplicate]

I know of an explanation that the Earth is a inertial frame of reference since it is rotating about its own axis, and since this is happening there is a centrifugal "force" or effect which counters ...
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1answer
188 views

How to calculate the cooling timescale of a giant planet [closed]

I have the following question from my Astronomy class. Show that the cooling timescale of a giant planet scales linearly with radius. Assume that its thermal energy content is proportional to ...
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1answer
71 views

Where is the mass and gravitational influence of dark matter? [duplicate]

I'll have to ask an elementary level question about orbital motion and the mass/gravity that influences it. In solar systems, the large mass of the sun pulls on the planets and we see the velocity of ...
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2answers
485 views

Why does this planet (J1407 b) and Saturn's ring center on its equator? [duplicate]

Why is the material in J1407 b's or Saturn's rings stay in a disk not scattered? Is it the gravity and/or magnetic field that causes this? Does it differ with other large bodies that might not have a ...
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1answer
282 views

How much mass is needed to curve spacetime and attract another mass?

How much mass would an artificial mechanical planet need to have to curve spacetime enough so that a smaller artificial planet/moon would be attracted to it? And let's say we put this artificial ...
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1answer
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When would Earth's Moon's gravity take over? [closed]

At which point would an object stop being pulled from Earth and towards the moon? Could a light weight rope be tethered to the moon with the object over on Earth's gravity's side? Can it be done and ...
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2answers
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How many arcseconds the light of a star unfolds in the vicinity of jupiter?

One of the main demonstrations made to test the theory of relativity were the images of the solar eclipse of May 26, 1919, (causing a shift in the positions observed in celestial coordinates of its ...