Stack Exchange Network

Stack Exchange network consists of 174 Q&A communities including Stack Overflow, the largest, most trusted online community for developers to learn, share their knowledge, and build their careers.

Visit Stack Exchange

Questions tagged [planets]

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

-1
votes
2answers
62 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 ...
1
vote
3answers
131 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 ...
0
votes
2answers
136 views

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 ...
0
votes
1answer
45 views

How to make a planet out of krypton? [on hold]

Let's suppose there is a star that explodes and releases a large mass of krypton. What is the smallest mass of krypton necessary for a planet to form made entirely of krypton under the attraction of ...
0
votes
2answers
52 views

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 ...
-1
votes
1answer
44 views

How does an object's volume affect its gravitational pull?

Two instances. An object is in front of two different planets with the same masses, but two different volumes. How does the gravitational pull vary from each planet? I am thinking with more given ...
5
votes
5answers
114 views

How can an electrically neutral planetary core be geodynamo? [duplicate]

The standard theory for the earth's magnetic field is that the planet's core is a geodynamo. I know moving electric charges can induce a magnetic field, but I also know that opposite charges produce ...
3
votes
0answers
30 views

What if an ocean planet is covered by superfluid ocean? [closed]

It is possible that an ocean planet can be covered by superfluid state liquid. What will happens on this kind of planet? Will there be any changes to tide? Will there be strong magnetic field? Will ...
1
vote
1answer
64 views

Sound and gravity

How would heavier gravity (or lighter gravity) affect sound in terms of what I hear? For example, say there is a planet that is capable of supporting human life, but it has heavier gravity than ...
1
vote
1answer
58 views

What is the second $r$ in this equation for the Two Body Problem?

$$r=\frac{r^2\frac{\mathrm d\theta^2}{\mathrm dt}}{\frac{Gm_2^3}{\left(m_1+m_2\right)^2}\left(1+e\cos\theta\right)}$$ I have this equation for the radial distance of a planet from the barycenter. But ...
-2
votes
1answer
46 views

Bad value for sphere of influence with Venus [closed]

I would like to get value of sphere of influence than Wikipedia for Venus: on https://en.wikipedia.org/wiki/Sphere_of_influence_%28astrodynamics%29 It is indicated for Venus: $S_{\text{OI}}=0.616\,\...
7
votes
1answer
470 views

How do we know the Earth's core is Molten with Seismology?

My current knowledge about how the core of the earth was discovered is the observation made from non returning/reflecting sonar signal when sent to deeper depths through the earth's crust/mantle. How ...
1
vote
1answer
58 views

How did Mars lose all its surface water?

A lot of geological evidence suggests that Mars once had quite a bit of surface water. I assume it wasn't whisked away into space, so where did it all go? What processes caused the water to go there? ...
1
vote
2answers
93 views

Accurate Equation for Earth's Gravitational Binding Energy

This is a relatively important question for anyone who can answer it. I am trying to find the equation that accurately solves for Earth's Gravitational Binding Energy. The information below is from ...
2
votes
1answer
24 views

Earth bulge and axis precession

We know that earth is not spherical because it spins. Does every object that spins bulge? for example a rotating wheel bulges? Also how moon and sun create the torque that shifts the axis of rotation (...
1
vote
2answers
53 views

Why do gas giants have similarly coloured stripes?

After looking at Jupiter and searching 'exoplanets gas giants' on google I found that many had stripes on them. I found that pretty peculiar. So why do they have stripes. I think it has something to ...
0
votes
1answer
64 views

Digging a hole in the moon across its diameter [duplicate]

What will occur if one digs a hole in some moon/dead-planet without an atmosphere (and without a Lava Core), such that this hole shall have a 1 meter diameter and will be so deep that shall go through ...
1
vote
0answers
17 views

How severe would the consequences be if the earth's moon were wrenched from orbit?

The old TV series Space 1999 from the early 1970s seems to have resurfaced on Youtube reminding me of something I watched as a child. It is one of those obviously ridiculous SciFi series (from the ...
8
votes
3answers
891 views

Gravitational advantage of outer planets in war

The Expanse books cover a lot of aspects of war in a situation where humans inhabit many planets and moons of the solar system. The author makes the point that, in a war situation, the outer planets ...
-1
votes
3answers
98 views

The acceleration in Earth's gravity

The acceleration in earth's gravity is $9.807 m/s^2$ at my location. But is this value uniform in the entire earth? For example in the inner core or outer core. What is the acceleration in the center ...
3
votes
2answers
94 views

Relativistic space rocks. Are they possible?

I was thinking that the Universe is full of extreme events. Colliding galaxies, exploding stars, colliding planets (like in one of models of our Moon formation), colliding black holes... Can it be ...
-1
votes
0answers
22 views

How to measure the contraction of a planet using the virial theorem?

Say one wants to measure by how fast a planet is contracting ( i.e. it appears to be radiating more energy than it absorbing at a ratio of 2:1). Then using the virial theorem $$PE+2KE=0\tag{1}$$ ...
35
votes
12answers
12k views

If gravity disappeared, would Newton's third law make everything that was pressed to the ground by gravity get pushed upwards? [closed]

If gravity disappeared, would Newton's third law make everything that was pressed to the ground by gravity get pushed upwards?
-5
votes
3answers
141 views

Why is Mars so cold when it has so much atmospheric $CO_2$?

Mars has 1/10 of Earth's atmosphere but that atmosphere is 95% CO2. Why is Mars so cold when it has so much atmospheric CO2?
1
vote
1answer
26 views

Gravitational/electromagnetic effect of planets on solar activity?

Does the gravitational and/or electromagnetic influence of planets have any effect or correspondence to solar activities (e.g. solar flares/CMEs) - and if so, does the planetary position (where they ...
0
votes
1answer
23 views

What's the difference between a convection and a polarization electric field?

In the ionosphere and magnetosphere communities, studies frequently refer to the "convection electric field" and the "polarization electric field". What is the relationship between them, and what are ...
1
vote
1answer
27 views

Can a planet have multiple significant sized moons?

The Earth has one moon at about 1/80 of Earth's mass. Is it possible to have two moons large enough each to subtend a >30 minute disk as viewed from the surface? I have tried with various ...
0
votes
0answers
40 views

How fast would the Earth have to spin to lose the atmosphere?

I have read these questions: How fast would the Earth need to spin for us to feel weightless? Why can't we feel the Earth (or being in any non-inertial frame) rotating? And it made me curious....
-5
votes
2answers
88 views

How do astronomers explain trajectories of planets?

I'm wondering how astronomers can explain the trajectories of planets because: planets spin, so have angular kinetic energy. Thanks to the mass-energy relationship this means space-time curvature. ...
1
vote
1answer
36 views

The Earth's Equatorial Bulge [duplicate]

It is stated that the Earth is a 'squashed sphere' due to the very slight bulge at the equator. (Thought in reality it's such a small difference, it's essentially spherical) Typical values: ...
0
votes
2answers
127 views

Does the Earth emit heat?

I'm reading my first book on physics "Seven brief lessons on physics" by Carlo Rovelli, and in his chapter on "Probability, time and heat of black holes", he mentions that Stephen Hawking showed that ...
2
votes
3answers
105 views

Why should asteroid coming towards a star deflect away from star if gravity is an attractive force?

I was finding the closest approach of an asteroid (whose energy is sufficient to exit the gravitational field of the star )so that it can escape the gravitational field of the planet .The asteroid ...
2
votes
1answer
115 views

How would the rotational and orbital mechanics differ on a torus-shaped planet as compared to a spherical planet? [closed]

I am making the attempt to develop some computational models of Star systems and I was wondering how the a torus shaped planet would compare to a traditional spherical planet in the context of ...
1
vote
1answer
75 views

Is there any moon without its planet?

Is there any planet without its star? Is there any moon or any planet wandering in outer space without a definite orbit? (The name moon or planet used here serves only for size and spherical shape ...
1
vote
1answer
97 views

Could there be a minimum black hole within each moon, every planet, every star?

It's the spherical aspect of these celestials bodies that makes me think about this. Could planet Earth have started itself with a tiny black hole?
3
votes
2answers
118 views

Why do all the planets and stars in our solar system have such similar average densities?

This table lists the average density of all the planets in our solar system. We could also consider the Sun (average density 1.41 g/cm³) and Pluto (average density 1.88 g/cm³). The densest body (Earth)...
0
votes
3answers
45 views

Planetary Gravitational Pull

I have read that Jupiter and Saturn apparently have no surface. I have a hard time believing that a ball of gas can have such a strong gravitational pull without any kind of a solid surface. Can ...
0
votes
1answer
45 views

Planet Orbital locations based on year / month. (table?)

I am finalizing an Orrery that used Arduino to move planets into their respective orbital position based on the year and month from a users input. I am looking for a table or database that has the ...
-1
votes
4answers
232 views

What is acceleration due to gravity at the centre of the earth? [duplicate]

When I asked my teacher that what is the acceleration at the centre of earth, he replied that it is 0 as when we move inside the earth, the effective mass decreases i.e. the mass that exerts ...
7
votes
1answer
469 views

Arbitrary Planet Spectrum

During my revision for an astrophysics quiz, I have encountered a question where I don't know where to start because I feel like I am lacking some intuition. I would appreciate any feedback! ...
1
vote
0answers
44 views

Gravity train and fastest path

As a fun exercise to kill some time, I have been thinking in the gravity train. For a point mass falling through a tunnel dug from pole to pole in an spherically symmetric planet of radius $R$, the ...
0
votes
0answers
23 views

Good books on Venus?

I'm looking for good books on Venus. I need some more general and some specifically about the atmosphere and atmospheric waves. Any detailed, complete and well structured book references are welcome.
0
votes
2answers
69 views

Question about the Normal Force exerted by Planet Earth in relation to centripetal force

I have the following question based on a paragraph from my Physics textbook (I am translating, so the result might not be the most elegant): It states that due to the centripetal force resulting from ...
0
votes
1answer
35 views

Why is the Earth not an exact sphere and what makes it bulge at the equator? [duplicate]

In chapter 7 of the Feynman Lectures Volume 1, Feynman explains that the Earth is round due to gravitation as everything attracts everything else. He also says that it is not an exact sphere since it ...
-1
votes
1answer
49 views

Can a tunnel through a planet be used as a power generator?

Assuming that it were possible to do so, if a tunnel from one side of a planet to the other were lined with copper wire, could dropping magnets down the hole be used to generate power?
0
votes
1answer
25 views

Earth-like atmosphere on Mars, possible?

I recently watched a TED talk by a journalist, Stephen Petranek, in which he talks about colonization of Mars. Reaching the end of the presentation he talks about terraforming the planet, making it "...
2
votes
3answers
86 views

I don't understand why pressure should increase with depth into a sphere

Newton demonstrated that the gravitational force at a distance r from the center of a uniform sphere is "as if" all the mass was concentrated at the center. The proof I have seen starts by first ...
0
votes
1answer
20 views

Difference between solar annual and solar daily earth tides

I understand there is a semi-daily and daily solar earth tides (S1,S2) because the earth is rotating around its axis. I understand there is an annual and semi-annual solar earth tides (Sa, Ssa) ...
0
votes
2answers
61 views

Effect of Change in Mass on Planetary Motion [closed]

How would a change in the mass of a planet in the solar system affect its orbit? For example, if hypothetically the mass of Mars were doubled, would it [a] move closer to the Sun, [b] move further ...
1
vote
1answer
57 views

Is it possible for a planet or a moon to exist with absolutely zero atmosphere?

Mercury has an atmosphere, no matter how thin that might be. Scientists say that the space is not completely empty because we can always find a few hydrogen atoms per kilometer all over the outer ...