2
votes
1answer
19 views

Are retrograde capture orbits “easier” than prograde capture orbits?

After reading up on irregular moons in the solar system - moons that are thought to be captured, most seem to be in retrograde orbit around their parent body. That led me to wonder if retrograde ...
0
votes
2answers
55 views

A small object on the opposite side of the earth's orbit with 0 velocity,“in line” with the core - would it collide with the earth?

If a small object (say mass 1 kg), at the opposite side of the earth's orbit (six months away), was placed in the same orbital position as the earth's core, at zero velocity in all directions, would ...
4
votes
3answers
103 views

Using 2D position, velocity, and mass to determine the parametric position equations for an orbiting body

I have a gravity-related question. I am programming an orbit simulator. I have everything up and running, but I would like to render the smaller body's orbital path (the larger body is fixed). To do ...
4
votes
5answers
237 views

Does Gravity / curved space cause rotation?

Does Gravity / curved space cause rotation? Meaning, if a spaceship is heading not directly toward Earth, but slightly off to one side, and when finally being close to the Earth it falls into earth ...
3
votes
3answers
185 views

What is the reasoning behind the Hill Sphere?

According to Wikipedia, Hill Sphere is : the volume of space around an object where the gravity of that object dominates over the gravity of a more massive but distant object around which the first ...
0
votes
2answers
96 views

A revolving astronaut

The concept of orbital velocity tells us that there must be a minimum velocity for a satellite to revolve around earth and the velocity should be such that the gravitational force of earth provides ...
0
votes
1answer
71 views

A change in the mass of the moon [closed]

Would a change in the mass or radius of the moon have any effect on its speed? When asked this question in an assignment, I stated that it did not. My reasoning being that a change in the mass or ...
4
votes
2answers
365 views

Calculating Orbital Vectors in the Future

For the 2D space simulator that I am writing (please note, it is not at all homework), I require formulas that will give me the location and velocity of a spaceship, relative to the parent celestial ...
1
vote
0answers
36 views

Where are the L3, L4, and L5 of a hyperbolic orbit?

Do the L3, L4, L5 points exist in hyperbolic orbits? If yes, then where do they lie?
1
vote
1answer
84 views

Perihelion Advance in curve space

I've been doing some work that involves particle's motion subjected to central forces. I was trying to compute the perihelion advance of the particle's path. For that I've been following this ...
3
votes
1answer
128 views

How can you calculate the tidal gradient for an orbit?

In the movie Gravity, two characters are dangling from the international space station by a long tether. I've previously wondered exactly how you could calculate the tidal forces that act on an ...
1
vote
1answer
72 views

What is most infeasible about a sky hook (as in space travel not Batman)?

We need to get things into space but it costs too much. Lots of people talk about space elevators but no one talks about the skyhook idea. I'm referring to this: Skyhook (Wikipedia), not the thing in ...
4
votes
2answers
173 views

Gravitation not instantaneous = non elliptic orbits?

When I studied physics some time ago my teacher explained that if we consider the gravitational atraction not instantaneous, such as the General Relativity says, the planets would be attracted towards ...
3
votes
3answers
181 views

How does the gravity of a massive non-spherical object act on things around it?

Firstly, not sure if this question ought to be in the space SE site. Please let me know if it should. (Posted in both for now) Secondly, I don't know a whole lot about physics (I'm just inquisitive). ...
-1
votes
2answers
70 views

orbitting around the earth

Does a space station need an initial velocity (tangentially) to be able to orbit around the earth or just the gravitational force acting downward on the station at certain height from the ground is ...
3
votes
2answers
144 views

Orbit reversal in a gravitational well

A friend recently asked me this, and without wishing to spend a huge time thinking about it, I wondered if anyone knew the answer (or at least had an informed guess), or was familiar enough with these ...
3
votes
1answer
181 views

Binary star system - Revolution around Primary vs Companion

How likely is it in a binary or multi-star system for a non-star celestial body to revolve around the primary star rather than the companion star?
2
votes
2answers
141 views

How do you travel in a circular orbit around a massive body?

I am trying to figure out how an object could achieve a perfectly circular orbit. Given a mass for the planet or other body the object is orbiting and a distance from the center of mass, how fast ...
2
votes
2answers
421 views

Can the mass of an orbiting object and the object being orbited be determined by the distance and orbit velocity alone? [duplicate]

This question is the inverse of: "Could an object orbit while moving at twice the speed, but at the same distance, if it had half the mass?" I'm curious about the nature of orbits, but am not well ...
3
votes
4answers
289 views

What causes matter to initially rotate/spin/orbit?

What causes matter to initially rotate/spin/orbit? All I can find is the statement that in space particles of dust/gas/matter contract into a spinning disk due to gravity (to form stars, solar ...
1
vote
1answer
178 views

Solving equation of motion of two massive particle exerting the gravitational force each other

I'm trying to analyze the motion of the particles which exert the gravitational force each other. Let $M_1$, $M_2$ be the masses of the particles, and the equation of motion of particle $M_1$ $$ ...
5
votes
2answers
186 views

Practical limits on the size of orbiting objects: could two pebbles orbit each other

As I understand it, gravity is inherent to mass and therefore even a small rock has its own gravitational pull. It seems entirely plausible then that a rock 1" in diameter could orbit a bigger rock, ...
2
votes
1answer
107 views

Acceleration due to gravity?

I was looking into orbitals and found something I haven't been able to understand. http://www.math.ubc.ca/~cass/courses/m309-01a/hunter/satelliteOrbits.html There is a part on the page which states ...
1
vote
1answer
140 views

Defining the star as the ellipse focus rather than the barycenter, what does the other focus do? [duplicate]

There are a lot of images and animations on the internet depicting two bodies orbiting around their common barycenter. The barycenter is defined as the (let's say right) focus of the ellipse. If we ...
4
votes
1answer
95 views

Gravitational resonances for satellites

I read on the website of European Space Agency that the altitude of Galileo satellites, which is 29600 Km from the center of the Earth, is chosen to avoid gravitational resonances so that station ...
5
votes
1answer
175 views

Orbital mechanics and rocketry: Is it ever a good idea to intentionally lower periapsis?

tl;dr: Hohmann Transfer appears to be the optimal way to achieve a circular-to-circular orbit, but is it possible to lower the periapsis in order to achieve a more elliptical orbit with apoapsis at ...
4
votes
2answers
110 views

Orbit in the vacuum

As the space is a vacuum and there is no friction in space, Can we assume that, if we place an object in gravity in exactly the right distance from a planet with gravity and in the right acceleration, ...
1
vote
2answers
50 views

Solar Catastrophe [duplicate]

Consider all of sudden the sun vanishes. What would happen to planetary motion. Will it continue to move in elliptical path or move in a tangential to the orbit immediately after sun vanishes or move ...
-1
votes
2answers
234 views

General Relativity & Kepler's law [duplicate]

According to Kepler's law of planetary motion, the earth revolves around the sun in an elliptical path with sun at one of its focus. However, according to general theory of relativity, the earth ...
1
vote
4answers
118 views

Constructing an orbital trajectory that quickly returns to its origin

I'm working on a science fiction story that involves two spaceships engaged in combat while in orbit around a planetoid. My original idea called for spaceship A to trick spaceship B into firing a ...
4
votes
3answers
211 views

Is there a mathematical relationship here or am I looking for relations when there are none?

When I was taking classical mechanics, we dealt a lot with pendulums, and orbiting bodies problems. This lead me to think about the two situations depicted above. Left: Shows two balls of equal mass ...
3
votes
2answers
353 views

Deviation from Earth's orbit

How much orbital deviation is required for the Earth to get knocked out from current orbit so it either moves away from Sun or towards the Sun?
48
votes
5answers
3k views

Is there a small enough planet or asteroid you can orbit by jumping?

I just had this idea of orbiting a planet just by jumping and then flying upon it on its orbit kind of like superman. So, Would it be theoretically possible or is there a chance of that small body to ...
4
votes
1answer
161 views

Is the fuel burn for a satellite launch affected by the position of the moon relative to the launch site?

The gross mass of a satellite rocket is tiny compared to that of Earth, and Luna. Between them, however, the two bodies set up tides in bodies of water which itself is again considerable mass. At ...
2
votes
3answers
1k views

Could we make a trebuchet that could launch objects to a stable orbit?

Inspired by this xkcd, which calculated the energy requirements for accelerating individual humans to escape velocity (regardless of consideration for what that would do to your organs), I am ...
4
votes
2answers
372 views

Consequences of destroying a space elevator

Suppose there is a fully functional space elevator built on Earth. The base is attached to coordinates $ (\lambda, \varphi) = (0,0) $ e.g., on the equator on the zero-meridian. What would happen ...
2
votes
3answers
323 views

The theory of moon creation when a Mars size planet hit Earth

As we know the predominant theory where does the moon come from is that a Mars size planet hit the earth and took a chunk out of it which eventually materialized into moon. My question is that if a ...
1
vote
1answer
156 views

Determining Orbital Velocity

Is there any way to determine the orbital velocity of a point around another stationary point, if I don't know the mass of either of the points but know the force that gravity exerts and the distance ...
2
votes
3answers
227 views

Can a photon be made to orbit a known (or undiscovered theoretical) body?

Can a photon through some process be made to orbit a celestial or any other object? Two follow-up questions. Can this orbit be described as the photon crossing its own path. Will this ...
0
votes
1answer
78 views

Space station gains enough mass to lose orbit?

I.S.S is constantly being improved (add-ons). Will the space station need to be moved to a higher orbit at some point?
0
votes
3answers
158 views

Apparent non-aberration of gravity waves

Since GR assumes that gravity waves travel at speed c, we expect we would be able to some day detect an aberration effect similar the that of light. Of course, gravity waves are so tiny in magnitude, ...
7
votes
3answers
231 views

What exactly is the microgravity field in orbit?

The ISS and other objects in orbit still experience small acceleration outside from the perfect line of orbit (of the system CM). For instance, two objects in the ISS that are let to be at rest will ...
3
votes
1answer
585 views

About binary stars and calculating velocity, period and radius of their orbit

I saw somewhere about being able to measure the velocity, period and radius of a binary star orbit by looking at red shift and blue shift. I understand it but can someone give me an example of ...
4
votes
4answers
1k views

Increasing mass' effect on the balance between centripetal force and centrifugal force

Okay, this is nothing more than a thought experiment which popped into my head while driving home from work today. Take the case of a single body orbiting another, larger body, as in a planet and a ...
2
votes
1answer
711 views

Do all planets rotate around the sun with the same acceleration?

I have this question in mind. suppose if by any chance, all planet around sun stopped rotating. then as per formula F= M * A. all planet should fall with same acceleration towards sun and ultimately ...
2
votes
3answers
975 views

Initial vs Constant Orbital Velocity

I am working on some basic physics simulation for a game and need to simulate gravity. I have a system working that is behaving more or less correctly so far, but I want to see if I can send a ...
3
votes
2answers
78 views

Computing period, semi-major axis of binary

I have mass, $g$, and luminosity of each of the stars in a binary system, extracted from a model. I calculated the individual radii from $g$ and the mass. I am trying to compute $a$, but I seem to be ...
3
votes
4answers
806 views

Two masses in deep space - collide or orbit?

If two identical masses are somehow "released" into deep space (that is, they're subject to no other gravitation forces but their own, and are initially at rest to each other). What decides whether ...
33
votes
2answers
1k views

Why are our planets in the solar system all on the same disc/plane/layer?

I always see pictures of the solar system where our sun is in the middle and the planets surround the sun. All these planets move on orbits on the same layer. Why?
4
votes
3answers
390 views

Why don't astronauts in orbit get stuck to the “ceiling”?

When a shuttle is in orbit, it is essentially rotating around the "centre" of the Earth at a great speed. So why does there seem to be no centrifugal force sticking them to the 'ceiling' of the ...