# Questions tagged [planets]

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

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### Does gravity get stronger the higher up you are on a mountain?

So I saw this article stating that gravity is stronger on the top on the mountain due to there being more mass under you however I have read some questions other people have asked and most of the ...
76 views

### How do I calculate Earth's velocity?

How do I calculate Earth's velocity (on its elliptical orbital path, as a function)? I know how to calculate it assuming that Earth's orbital path is circular but I want to know what we would do if we ...
28 views

### How do I calculate the moment of inertia of an idealized Earth's equatorial bulge?

I am working on calculating an idealized Sun-Earth-Moon three-body system. As part of this I want to calculate Earth's axial precession, which requires knowing the torque that is acting on it. ...
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### What causes Saturn's hexagon hurricane? [duplicate]

Recently, Tien Nguyen JPL Fellow - Chief Engineer at NASA Jet Propulsion Laboratory, did share this photo that says "Cassini catches an awesome glimpse of Saturn’s north pole hurricane" I ...
151 views

### What would be the color of a deep, pure and vast liquid $\rm CO_2$ ocean if viewed from space (ignoring the atmosphere's influence)?

So far I had no luck trying to find the visible absorption spectrum of $\rm CO_2$ anywhere, all I get is the far infrared absorption spectrum and stuff like that. If you just search "what color ...
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### Can we cool Earth by shooting powerful lasers into space? [closed]

In a sense, the climate change discussion revolves around the unwanted warming of the earth's atmosphere as a whole. It seems a bit too obvious to be true, but could we cool the atmosphere by simply ...
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### Liquid metal p-trap entry into an underground base on planet Mercury

Imagine we one day establish a colony under the surface of planet Mercury and use integrated thermal acoustics to stabilize the subterranean environment. With a both heat and cold storage available, ...
4k views

### Can a person on the equator jump up higher into the air at sunset than at sunrise?

I am wondering if a person on the equator can jump up slightly higher into the air at sunset in comparison to jumping up into the air at sunrise. The reason for this would be that at sunset the Earth ...
40 views

### Why doesn't earth have a hydrogen atmosphere if hydrogen's thermal velocity is 1.75 km/s - less than 1/6th of earth's escape velocity? [duplicate]

I have read that in order to retain a gas, a planet's escape velocity must be at least six times the thermal velocity of that gas (I understand that this is just an approximation of the Maxwell ...
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### Winds on gas giant planets: Would they increase if closer to their star?

The planets Saturn, Uranus, and Neptune are all primarily heated by their internal radiated heat, not by the Sun. Each of them have rotational periods shorter than that of Earth despite their much ...
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### Independence of Gravitational acceleration with depth if local density of earth is 2/3 of average density

Show That the acceleration of gravity in a vertical mine shaft is independent of the depth if the local density of the Earth is 2/3 of the average density. Assume that the Earth is a spherically ...
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### Should larger rocky planets eventually crack due to temperature differences between their inner and outer layers?

Should larger rocky planets eventually crack due to temperature difference between their layers? When a tick piece of glass is left to cool down it would eventually crack...but this is caused ...
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### What's the minimum possible size of a round astronomical body?

What's the minimum possible size of a spherical shaped rocky planet or satellite? Is it possible to occur a spherical shaped planet without having a molten core?
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### Proving nearby planets are not antimatter [duplicate]

Observations of the universe make us think matter is much more common than antimatter, and I believe no "probably-antimatter planets" have been found. But, if Pluto, for example, somehow ...
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### Saturn's moons - getting a stable harmonic model for Mimas and Encyladus

I have built a HTML/Javascript solar system model. It is working well with real time animation. https://abetz-rouse.com.au/planetarium I don't want to get into the deficiencies of my choice of ...
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### Doubt regarding elliptical orbits and eccentricity relation with masses

I was working with Roche's Limit , You can visit the wikipedia page on Roche's Limit and Hill's Sphere (not important here). A query raised in my mind about the elliptical orbit in which the moon is ...
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### What is the meaning of grain opacity and why does it affect the formation time of gas giants?

While doing research for my presentation on the formation of gas giants, more specifically the "core-accretion model", I have been stumbling across the term "grain opacity" and don'...
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### Why doesn't the Earth's temperature increase in the perihelion?

I know that what causes seasons in earth is the tilt of the earth and the fact that sun rays reach the earth from different angles during winter and summer, but why doesn't the temperature of the ...
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### For Newton's gravitation equation, how do you account for planet size?

My daughter was doing a physics problem where she had to calculate the gravitational force of an object that was 250 km above the earth... She used the equation: $$F=\frac{G\cdot m_1 \cdot m_2}{r^2}$$...
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### Which force provides the centripetal acceleration that makes objects on earth's surface rotate about Earth's axis of rotation?

Let's say an object is at rest in Earth's reference frame. We know that Earth's reference frame is non inertial. If we were to observe that object from an inertial frame, we would see three forces ...
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### What would happen if a tungsten rod massing 1000kg slammed into the surface of Callisto at 15% of the speed of light? [closed]

I am writing a sci fi story and I want to know what would happen if a tungsten rod massing 1000kg slammed into the surface of Callisto at 15% of the speed of light? Given that there is a subsurface ...
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### Is drinking water an important feature for finding habitable exoplanets? Has it been found?

We need drinking water to live on other planets. Has drinking water been found on other exoplanets? Is drinking water an important feature for finding habitable exoplanets? I want to (self) study in ...
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### In a 2-dimensional sense, how do the perihelions of the planets in our solar system line up?

A bit of background, I'm currently making a 2d graphical representation of the planets orbits around the sun with Python for a university project which currently looks like the picture below (not ...
16 views

### Looking for a formula or model for planetary equilibrium temperature which takes into account the greenhouse effect

For a project I'm working on, I have made a bunch of hypothetical random planets orbiting random stars. I have come across the Stefan–Boltzmann law, which works nicely for any planet without an ...
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### Is there any evidence that atoms behave differently on other planets? [closed]

I know gravity, atmosphere density and other values would be different on other planets, but is there any evidence that intrinsic atomic properties (i.e. melting point) are different on other planets?
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### Claims of detection of gravitational waves with an accelerometer

Is this claim: https://earthscience.stackexchange.com/q/21236/ of detection of gravitational waves with accelerometers legitimate? I do not know much about this, but given how gravitational waves form ...
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### Is there a gas present in the Martian atmosphere similar to hydrogen?

is there a gas present in the Martian atmosphere which could be extracted to inflate a balloon with sufficient lift to support an instrument platform for low altitude reconnaissance.
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### Have Einstein's field equations ever been solved for Earth? [closed]

If not, what remains unknown that prevents a solution?
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### What determines the magnitude of the atmospheric scale height of a planet?

What determines the magnitude of the atmospheric scale height of a planet? https://en.wikipedia.org/wiki/Scale_height says that: "Approximate atmospheric scale heights for selected Solar System ...
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### Could the hypothetic water bodies on Mars be 'stable' only if they were large like Earth's oceans?

Could the hypothetic water bodies on Mars be 'stable' only if they were large like Earth's oceans which needs macroscopic basins? Are possible rivers and lakes enough to ,mantain all the water.As ...
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### What would happen if the Earth was hollow and somebody rode on the “inside shell”?

I'm having a difficult time understanding basic centripetal force, forgive me. On the earth as it currently is, if you fall off a cliff you will fall closer to the core. However on a cylindrical ...
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### Had the centrifugal force of the rotation of Earth in the past forced liquid, hot Pangea to be positioned near the Equator?

Had the centrifugal force of the rotation of Earth in the past forced liquid, hot Pangea to be positioned near the Equator? Maybe also a question for 'GSE' but if we deal with centrifugal forces and ...
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### Did we adapt to Earth or Earth to us? [closed]

I often hear that Earth is a unique planet because it has life and it has its own inhabitance. We also see a proper balance between plants and humans and other animals. Why life is not possible on ...
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### Our sky is blue. Would a planet that has 1% of earth's atmospheric density have the same colour sky assuming the sun is exactly the same as ours?

If not then which colour would the sky be and why? Could you determine which elements the atmosphere is made of just by looking at the colour of the sky? Is it possible to know the density of a planet ...
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### What adjustments are needed to use Newton's Law of Universal Gravity to calculate the force between me and Earth?

Background Say I weigh $80 \mathrm{kg}$, and I happen to fall to the ground with an acceleration of roughly $9.81 \frac m{s^2}$, I would, using Newton's second law of motion, $F = ma$, come to the ...
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### Does bottle water rise a little bit on full moon days?

High tides and low tides are caused by the Moon. The Moon's gravitational pull generates something called the tidal force. The tidal force causes Earth—and its water—to bulge out on the side closest ...
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### How bright would the surface of each planet be?

At night when there is no moon in the sky, it is dark, you can not see your surroundings. If I were to stand on Pluto, could I see my surroundings? Would being on pluto at day be like night on earth ...
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### Where from is the distance calculated in Newton's law of universal gravitation?

In the equation for universal gravitation $(1)$ between two objects, where from is $r$ calculated? From the surface, from the center? Also, are the objects assumed to be particles in this equation or ...
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### Why can gravitational potential energy be expressed both as $mgh$ and $-GMm/r$? [duplicate]

In these two different equations for the same (?) thing, not only is one directly proportional to height and one is inversely proportional to height, but they contain completely different variables, ...
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### Will the weight further increase while going inside the Earth? [duplicate]

Our weight is more at the pole than at the equator (because it is closer to the center). Does that mean if we go down into the earth (some kind of bore), will our weight increase further? I remember ...
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### Is General Relativity (GR) compatible with the expanding Earth hypothesis? [closed]

There is a lot of convincing evidence that the Earth and all the other planets and their moons are expanding with time. Prof. Samuel Warren Carey's summary of the evidence: https://www.youtube.com/...
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### How to track orbit of an exoplanet?

I was wondering if there is an established method to keep track of the orbit of an exoplanet assuming we know $a$ - the semi-major axis of the orbit, $e$ - the eccentricity of the orbit, and $i$ - the ...
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### Direction of acceleration in elliptical path

The $x$ and $y$ coordinates of a particle moving in a plane are given by x(t)=acos(pt) and y(t)=bsin(pt) where a, b(<a) and p are positive constants of appropriate dimensions and t is time. I know ...
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### How does Jupiter have two magnetic South poles and one magnetic North pole? Magnetic tripole?

Generation of magnetic field of Earth is relatively well-understood The magnetic field is generated by electric currents due to the motion of convection currents of a mixture of molten iron and ...
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### Is the point mass assumption valid for non-spherical objects?

In case of a shell or a solid sphere we can assume it to act as a point mass to calculate the potential and field for any object as long as it lies outside the shell/sphere. I have learnt the proof ...
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### Time spent by a comet inside the Earth's orbital (Kepler problem re-visit)

I come across this interesting problem comet-x-earth. It was an exam problem asking the time that a comet will be spent inside the Earth's orbital. I make an illustration for the problem: The comet ...
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### Conservation of energy for a planet [duplicate]

I was reading Lectures by Feynman (which are soo good at any qualification!) and he talks about how energy of a particular planet in our solar system is constant at all times $i.e, KE+PE= constant.$ ...
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### How are the locations of solar system planets expressed in their orbits?

and where can I find the data about the locations of the solar system planets during their entire year? I would like to find the data on the orbits of solar system plantes. Also I would like to know ...