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

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15 views

What would happen to a planet at the heliosphere's termination shock?

Assuming that a planet with an atmosphere already existed which orbits at the radius of the termination shock of a star, what would happen to it over time? As a follow-up, would it be possible for a ...
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2answers
984 views

What planets are visible to the naked eye from Mars?

Here on Earth we are blessed with being able to see some other planets, Mars & Venus etc, with the naked eye on a fairly regular basis thanks to the distance between the planets. What about from ...
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18 views

Books of dynamo theory

I wanted recommendations of dynamo theory pdfs to make a report about magnetic fields of planets and stars with all the math behind it, like vector calculus, Lagrange functions, partial differential ...
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0answers
61 views

Has New Horizons' visit to Pluto taught us anything deeper than mere… facts?

There's a lot of interesting stuff coming from New Horizons about Pluto, but are we actually gaining any non-trivial scientific understanding from it, or is it all just "oh neat, Pluto has mountains ...
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2answers
48 views

Calculate volume of a crater

Is there an equation I can use to determine the volume of a crater in my 'drop the ball on sand' experiment? I looked at the equations for volume of hemisphere and cone but do not seem to fit the ...
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3answers
60 views

What is the definition of potential energy? [duplicate]

I have problems with this equation: $$U_G ~=~ G\frac{m_1m_2}{r}.$$ It's for potential energy of say something placed on Earth. But it intrigues me. $r$ is the distance from the very center of the ...
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0answers
7 views

Region of resonance and overlap

In planetary dynamics what does a region of resonance (mean motion) between two bodies mean and how to quantify the region? How does resonance overlap occur and what are its consequences? What is ...
3
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1answer
58 views

Shoemaker-Levy 9 impact on Jupiter

When the comet Shoemaker-Levy 9 impacted with Jupiter it created a ball of fire 3000 Km high and it left a mark on the surface of the planet that was visible for weeks (source: Wikipedia). How was the ...
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1answer
70 views

Proportionality constant in crater equations

I have searched for equations regarding craters and I came across two of them. The first one is from this NOAO website in the level two section. There, it says that, $$ D^3\propto E $$ where $E$ is ...
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0answers
69 views

What is the likelihood that Kepler 452-b hosts or has hosted life? [closed]

Super excited with this latest discovery! For those unaware, NASA just released news on a "bigger, older cousin to Earth", named Kepler 452-b! Here's some more information (please feel free to correct ...
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2answers
52 views

Gravity underground on the moon?

They say that gravity Decreases as we dig into the earth. But I also read that gravity increases for the first approx. 2000km of distance underground. Using this rational, could we dig about 200 to ...
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1answer
59 views

Crater equation

I found this crater equation $$ D=0.07 \cdot C_f \cdot (g_e/g)^{1/6} \cdot (W p_a/p_t)^{1/3.4} $$ on a website, where $$ \begin{align} D &= \text{Crater Diameter}\\ C_f &= \text{Crater ...
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0answers
81 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 ...
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1answer
116 views

Why are tidal forces pointing away from the Moon?

I am currently reading The Science of Insterstellar, which explains most things very well, but some things leave me confuzzled, which I hope to get answers to here. I am no physicist, but highly ...
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1answer
600 views

How easily can the Earth flip?

The recent media attention to sunspot activity (however warranted) reminds me of a question I had long ago. Given the angular momentum and the slight 'wobble' of the earth, and remembering the ...
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2answers
44 views

What conditions would allow planetary-sized objects to collide and remain intact?

I am modeling some off-the-wall scenarios to try out with a game engine. One idea is trying to make a planet where some weird catastrophic incident has creates a funny shaped planet. I'm hoping to ...
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1answer
64 views

Temperature of planets without atmosphere

I am wondering how come a planet without atmoshhere loses heat in space when the space around it is a vacuum. In my understanding for one object to lose heat it must have contact with another ...
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3answers
71 views

How much force does it take to move the Earth? [closed]

If you could fly and survive in space, how much force would you need to move Earth at 1 meter per second?
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1answer
1k views

Correlation between speed, distance, mass, etc between a planet and a star (or moon and planet)?

While playing around with some little scripts, generating solar systems, I started to wonder about the correlation between the different objects. Up until now, distance, mass, size and speed are ...
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6answers
5k 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 ...
7
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1answer
188 views

Will Neptune change Pluto's orbit some day?

My seven-year-old son loves astronomy-- so much so that we read space books before bed time. One of our books talks about Pluto's orbit crossing over Neptune's orbit and will be (or is) closer to the ...
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1answer
98 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?
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1answer
39 views

Helium confined to a gravity well

It's a well known problem that Earth is slowly losing its supply of helium due to helium's ability to "bubble off" the atmosphere. All the gas giants have significant percentages of helium in their ...
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1answer
34 views

Motion of a ball in a tunnel along Earth's diameter [duplicate]

Suppose, a tunnel is made along the diameter of Earth and we drop a ball inside it. How will the ball behave? Please help me in the stand.
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0answers
33 views

Elliptical path of planets [duplicate]

Why are the planet's orbits in the form of an ellipse and what is the proof that earth moves in an elliptical path with the sun at its foci? Initially it was thought that earth moved in a circular ...
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0answers
34 views

How can a gas giant be said to have an atmosphere?

They are made of gas, right? So, there won't be a solid-gas or liquid-gas boundary that defines where the atmosphere starts. So, if there isn't a boundary, we can't define part of it to be an ...
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5answers
11k views

Would you be weightless at the center of the Earth?

If you could travel to the center of the Earth (or any planet), would you be weightless there?
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0answers
44 views

How to calculate the mass of a sun that is similar to our own

How would you calculate the mass of a sun that could host a habitable planet, with only given the values of the mass of our own sun. And the fact that it takes a specific amount of years for life to ...
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6answers
15k views

Why don't planets have Circular orbits?

This might be a completely wrong question, but this is bothering me since many days ago. Given the mass (Sun) curves the space around it, gravitation is the result of such curved space (Correct me if ...
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1answer
918 views

Atmospheric escape of gas molecules

Most of the objects in space are likely to have an atmosphere. Since space is void, the gases in atmosphere should have either dissolved or emptied into space. But, some of the objects still seem to ...
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2answers
97 views

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 ...
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2answers
2k 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 ...
3
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1answer
38 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
47 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
57 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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2answers
37 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 ...
22
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3answers
2k views

Why do the storms of Jupiter have long life unlike that of Earth?

Recently I saw How the Universe Works. In one of the episodes, concerning Jupiter, they told that the storms on Jupiter can survive many, many, times longer than those on Earth. What is the reason ...
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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
52 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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3answers
135 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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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 ...
13
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1answer
923 views

Falling into Saturn or Jupiter, would we pass through it until we hit the nucleus?

If we fall into Saturn or Jupiter, would we pass through it until we hit the nucleus? Or would we hit the surface and stop there?
2
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1answer
170 views
0
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1answer
59 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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1answer
36 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
366 views

Why do we orbit around the sun instead of one the other stars?

I am still very new to many physics theories, however while sat in class today, a thought came to mind that I have not been able to answer from simple googling. What is so specific about our sun ...
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3answers
103 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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2answers
113 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
78 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 ...
6
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2answers
382 views

Does a tidally locked planet have seasons?

Could a tidally locked planet have seasons? According to my understanding, a tidally locked planet rotates around itself exactly once per rotation around its sun. However, if the axis of rotation of ...