Questions tagged [planets]

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

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12 views

Recent/More accurate rotation velocity measurement?

I've been researching for papers for hours and can't seem to find this. Where can I find the most accurate equatorial rotational velocity measurement for Mars?
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1answer
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Do all the planets in our solar system orbit the sun in the same direction and in the same plane?

Do all the planets in our solar system orbit the sun in the same direction and in the same plane? (as in a flat orbit if you are looking from "above")
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Ever looming shadow

If I'm not mistaken the reason the moon eclipses the sun is because the ratio of distance to size, in regards to the moon and sun, is 1:1. And is it not also true that the reason we only ever see one ...
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Does frame-dragging affect planets?

The question has come up many times as to why the planets in our solar system lie in essentially the same plane. The most common answer is that they started out that way due to the accretion disk ...
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Equator water pipeline flow at sea level?

If a water pipeline was built at sea level eg. Gulf of Mexico and the other end was at sea level in southern Chile, then the pipeline was primed with pumps, would the water then gravity feed and flow ...
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4answers
138 views

Is the notion of 'weight of Earth' meaningless?

I am not talking about the distinction between mass and weight, just the concept of 'weight'. In University physics (book by Young & Freedman, 14th Ed.) it is given that the weight of an object ...
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On a planet with winds faster than sound, what would it sound like?

I'm watching a Youtube video of the strangest planets and some of them have atmospheres/winds that constantly go at like 20x the speed of sound, ex: HD 189733-b .On earth, fast winds is actually ...
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2answers
186 views

Confusion about a claim in the “Brief History of Time” by Hawking

In the first chapter, while talking about how Aristotle was able to conclude that the Earth is spherical, Hawking says that had the Earth been a flat disk the shadow of the on the Earth on the moon ...
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1answer
53 views

Why Earth’s crust is max 100 kms wheras Moon and Mars have much thicker ones?

We know that the Earth’ mantle and core are hot, whereas the crust has cooled down. The cooling process of the 4,5 billion years of the Earth’ exisence resulted a crust of between 50 and 100 kms. ...
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Ptolemaic system parameters

I recently learned about the Ptolemaic system, which seems pretty accurate. There is even a simulator on the Internet: https://astro.unl.edu/naap/ssm/animations/ptolemaic.html You can see that there ...
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Why doesn't Venus have a magnetic field? How does the speed of rotation affect the magnetic field of a planet?

Why doesn't Venus have a magnetic field? How does the speed of rotation affect the magnetic field of a planet?
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1answer
34 views

Can a planemo turn into a star?

I read this question Why is planet CFBDSIR2149-0403 hot? and wonder what will happen to this "planemo". Will it attract more mass as it flows around in the gas clouds in space and eventually light ...
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43 views

How hot can the surface of a planet be?

I just read this article https://edition.cnn.com/2018/07/02/world/newborn-planet-image-study/index.html and noticed that the astronomers estimates the surface temperature of the planet to 1000 °C. ...
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1answer
38 views

Mars longitude reference?

Platforms like NASA's JPL HORIZONS web-interface for solar system dynamics often have obtainable parameters like sub-solar or sub-terrestrial longitude for a given time and celestial object. (example: ...
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34 views

Uranus: The Spin

In his prog. , on the outer planets, Brian Cox stated that Uranus spins on its side because it once endured an interplanetary collision. Such a cataclysm would normally be devastating for both ...
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3answers
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Is there a maximum distance from a planet that a moon can orbit?

Given a planet that orbits a star, and a moon that orbits that planet, is it possible to define a maximum orbital radius of that moon, beyond which the moon would no longer orbit the planet, but the ...
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If the mass of the Earth is decreasing by sending debris in space, does its angular momentum also decrease? [duplicate]

We are sending huge amount of debris into space from earth, and also very heavy satellites and rockets, then the mass of earth must be decreasing over time. If the mass will decrease, then ...
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49 views

Jupiter & Saturn

In his prog. on Jupiter, Brian Cox stated that the complex gravitational interplay, between Jupiter & Saturn, prevented Jupiter from drifting through the Asteroid Belt, and approaching our part of ...
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How does the Earth remain in its shape?

I know only stars do nuclear fusion to keeps its shape from gravity. Then what about the Earth? Earth doesn't do nuclear fusion. How does the Earth keep its shape even though the gravity keeps pushing ...
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How to integrate acceleration due to gravity with height? [duplicate]

If I project a body at a very large velocity such that it reaches a height h which is comparable to Earth's radius, then how to derive an equation for 'h' in terms of initial velocity 'u' and other ...
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2answers
59 views

How does the gravitational acceleration on a surface of planet change, if its radius shrinks while retaining the same mass? [closed]

If the radius of the earth were to shrink by $1$% while its mass remained the same, then how would the acceleration due to gravity on the earth's surface increase by $2$%?
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2answers
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Do planets in elliptical orbits exhibit constant magnitudes of acceleration in their orbits?

I'm trying to reason through a problem. Consider Jupiter, which orbits the sun in an elliptical path. Is the magnitude of its acceleration constant throughout its orbit? My reasoning leads me to ...
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1answer
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How is sound affected by gravity?

How would sound be different on a planet with a stronger gravitational field? My reasoning leads to sounds of the same wavelength having higher frequencies - is this correct?
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In what planetary system can we have arbitrarily long winters?

Unlike on Earth where the length of seasons are almost of the same duration each time, the hypothetical planet on which Game of Thrones took place has seasons of arbitrary length i.e. some winters ...
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What is the hygropause?

I've been reading on planetary atmospheres and I've encountered this term which I can't find defined anywhere on the web. What is the definition of Hygropause?
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2answers
69 views

What will happen to atmospheres of very large planets?

Our earth can hold our atmosphere whereas Mars cannot. So the atmosphere retention mass must be between the masses of Mars and Earth, but if mass is to be considered then can an iron ball having the ...
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101 views

Anomalous precession of the orbit of Mercury

Can the anomalous precession of the orbit of Mercury be explained just with relativistic length contraction?
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1answer
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Earth rotation with atmosphere

Note: This might be a very dumb question Considering Earth's rotation on its axis, I was thinking it made sense for the outer sides of the Earth to have a significantly higher tangential speed, ...
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What happens to the heavy elements when a gas giant with no core or one with metallic hydrogen is formed?

I have been trying to visualize how a gas giant like Jupiter originally formed. I am assuming that in its early stages it formed by aggregation similar to how the rocky inner planets were with an ...
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2answers
86 views

Question about Earth being round, and whether a hypothetical scenario could be true [closed]

I am in no way, shape or form a physicist. This is a question I was debating in my head, and has nothing to do with flat Earth or protesting the Earth is not indeed round. I have a simple question ...
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2answers
71 views

Gravity below Earth's surface [duplicate]

Why is gravity reduced if you go below earth surface? Asked and answered before but I do not agree with the concepts followed in several answers. The concept of calculating the gravity attraction ...
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Heat transfer on Mars

SCENARIO: I have been tasked with finding the heat transfer across a composite wall on Mars. On the left of the wall there is air maintained at Earth atmospheric conditions and room temperature (101 ...
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Long-term fate of hydrogen atoms in a rogue planet

Imagine a rogue planet drifting in intergalactic space. For the sake of specificity, suppose that it is the size of Jupiter and composed of pure hydrogen. What will happen to it over the next $10^{...
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Calculating Inital Velocity required to stablize an orbit of a moon

I am currently attempting to create a little solar system simulation and I was curious if there's a decent way to calculate what a moon or planet's initial velocity would need to be to remain in orbit ...
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5answers
390 views

Do orbiting planets have infinite energy?

I know that planets can't have infinite energy, due to the law of conservation of energy. However, I'm confused because I see a contradiction and it would be great if someone could explain it. ...
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What orbit does a planet have to have to be a planet? [closed]

Other questions have dealt with where you could find a planet-like object, and what a planet has to consist of to count as a planet. But this question is directed as what orbit or path an object would ...
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2answers
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What would happen if a planet's escape velocity exceeded the speed of light?

What would happen if a planet's escape velocity exceeded the speed of light? Would it also collapse into a black hole (by Heisenberg's uncertainty principle and Pauli's exclusion principle) or would ...
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Does a star need to be inside a galaxy?

Must a star belong to a galaxy, or could it be completely isolated? In case it can be isolated (not belong to a galaxy), could it have a planet orbiting around it?
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1answer
38 views

Declination as a function of orbital position

Reading this Wikipedia article and following the derivations (https://en.wikipedia.org/wiki/Solar_irradiance#Milankovitch_cycles), I have found an equation I can't see where it comes from. Perhaps it'...
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1answer
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Can an elliptical planet be stable?

Subsequent to This question about the Earth's actual cross-sectional shape at the equator, I'm wondering about the stability of non-spherical planet-sized masses. Suppose there is a planet of uniform ...
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2answers
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How come planets with different masses can orbit at the same velocity at the same altitudes?

Angular momentum is equal to r × p and angular momentum is also what gives planets with lower orbits a higher speed (because angular momentum is conserved). So as r decreases either m or v (p=mv) has ...
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2answers
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How can I determine a planet's mass based only off of information about its orbit and its parent star?

I'm coding a video game with procedurally generated planetary systems and I want some and I want to make sure I'm at least somewhat scientifically correct. I've reached the part in my code where I ...
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If there was a hole in the north pole to the South Pole and you jumped into it how would would you come out feet first? [closed]

If I were to dig a hole in a round sphere Say the earth starting at the north pole standing on my feet I start to dig when I come out the other side would I come out of the whole feet first or head ...
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4answers
91 views

Does an object at the center of the Earth have potential energy?

"Potential energy: The energy possessed by a body by virtue of its position relative to others, stresses within itself, electric charge, and other factors." in other words, I think that potential ...
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Why spinning creates bulges? [duplicate]

Earth isnt a perfect but has bulges because of its spinning. What actually creates the bulges? Is the same reason that makes a liquid have v shape in a rotational tube?
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58 views

Treating stars and planets as a blackbody determine the temperature of a planet that has EM radiation incident upon it from a star

Consider the following question: Power emitted by the star via the Stefan Boltzmann law is as follows: $$4\pi\sigma T_s^4 r_s^2 $$ However the power will drop over distance and so we can say that ...
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2answers
77 views

Could a non-rotating planet, in a binary situation, have gravity?

Is it possible for a singular planet to rotate around a single sun in the same way that our moon rotates around the Earth? If so, would it be possible for that planet, if as large or larger than ...
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266 views

Why does angular momentum being constant prove Kepler's first law?

So I was watching this video and this video on Kepler's first law in order to understand the proof of Kepler's first law. He started off by saying that for an ellipse, the distance from a focus point ...
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Is it possible to have a planet entirely made out of liquid water?

Earth is mostly covered in oceans, but they only go a few kilometres deep. It's obviously not possible to have a planet the size of the earth to be made entirely out of water, because of the kind of ...
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How far can you pee on the moon vs. mars? [closed]

Let's suppose you are at Elon Musk's Future Mars colony and you drank too much beer, how far can you pee on Mars if you can pee one meter on earth? If the next day you get on the shuttle to the ...