The path a body takes while moving through space under the influence of the gravitational forces of other bodies

learn more… | top users | synonyms (1)

2
votes
1answer
279 views

Can we transfer burn to another planet at any time?

Assume delta-v isn't a problem and circular orbits. EDIT: Assume that you're already in orbit so you don't have to shift a massive load of fuel up, and the absolute ideal is something that has a ...
2
votes
1answer
2k views

Kepler Orbital Elements to Cartesian (xyz)

I'm not really sure if this is the place to ask this, but anyway here is my question: Let's say I have the Kepler orbital elements of the ISS, for example, (NASA stuff). Now I want to compute the ...
2
votes
1answer
817 views

How did Copernicus establish the relative distance to the superior planets?

I understand that the relative distances to the planets had been calculated using various methods since ancient times, and, in particular, that the assumptions of the Copernican model of the Solar ...
2
votes
1answer
334 views

Did Aristarchus take the radius of the Earth into account in calculating the distance to the Moon?

My text says that Aristarchus (310 BC – ~230 BC) measured the "angle subtended by the Earth-Moon distance at the Sun" ($\theta$ in the figure below) to establish the relative Earth-Moon and Earth-Sun ...
2
votes
1answer
25 views

Coexistence at Lagrange points

I was wondering how precise the location of an object in a Lagrange point needs to be to maintain stability, since it seems that several natural objects (asteroids) exists together in some of these ...
2
votes
1answer
48 views

How did Kepler formulate his second law from data?

It's amazing that Kepler derived his three laws emperically and then Newton rederived them from his own laws of motion. Its conceivable how Kepler derived the first and third laws, but the second law? ...
2
votes
0answers
34 views

Can a general n-body system emit gravitational waves?

I know that (for example) binary neutron stars can emit radiation in the form of gravitational waves. This question got me thinking about the case of three or more objects. I wrote in my answer that ...
2
votes
0answers
88 views

Do doomsday arguments influence doomsday hypotheses?

The doomsday argument supposes that in the absence of any other knowledge, if we know the age of something now, we may assume that we are seeing it in the middle of its lifetime and then calculate our ...
2
votes
1answer
69 views

Why doesn't no rotation imply tidal locking?

That I know of, in most parts of physics 0 movement means the body is resting, all the forces are in equilibrium. Why in orbital mechanic 0 rotation speed doesn't mean tidal lock as it would be the ...
2
votes
1answer
105 views

Unexpected eccentricity in moon orbit simulation

I've used Mathematica's NDSolve function to calculate the orbit of the Moon around the Earth. I used the following initial positions (perigee): ...
2
votes
0answers
35 views

What would the properties of a particle be that would allow light to orbit it? [duplicate]

What would the properties of a particle be that would allow light to orbit it? Light travels fast. Really fast. Almost to the point where we consider that it's instantaneous, and moves only in a ...
2
votes
0answers
123 views

How to calculate launch angle for tangentially launched satellites?

What is the value of theta for a satellite not falling back to the Earth if it is launched from the direction tangent to the surface of the Earth? I have found the escape velocity which is 11.18km/s, ...
2
votes
0answers
36 views

Would a large, small mass object in orbit experience induced rotation

Imagine a large (multiple earth radii), very small-mass ring orbiting The Sun. Half of the ring would be closer to The Sun than the outer half. Since orbital velocity decreases with distance, two free ...
2
votes
1answer
93 views

What is the constant $K_1$ in these orbital equations?

I want to compute the derivatives of argument of periapsis and longitude of the ascending node of the orbit of a GPS satellite from the following formula. $$\frac{d\Omega}{dt} = -K \cos{i} \\ ...
2
votes
0answers
92 views

Computing 2d Orbital Parameters

When using formulas that describe a 2d orbit around a planetary body: is it actually OK for the semi-major axis $a$ to be negative? when $a$ is negative, it is impossible to compute mean anomaly ...
2
votes
0answers
54 views

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

Do the L3, L4, L5 points exist in hyperbolic orbits? If yes, then where do they lie?
2
votes
0answers
88 views

How to travel between tidally locked binary planets

Two planets of roughly the same volume and mass are orbiting each other. What would be the most efficient way to travel from one to the other? Seems unlikely, but could a rocket positioned at the ...
2
votes
0answers
339 views

For two planets in a 2:1 mean motion resonance , where will their periastron and apastron points be?

I want to animate the changing orbits of planets when they enter a mean motion resonance. Using a 2:1 resonance, I want to show a low-mass inner planet and a low-mass outer planet being tugged by a ...
2
votes
2answers
298 views

The validity of the Longitude of Perihelion

As I understand it from Astronomical Algorithms, by Jean Meeus, the Longitude of Perihelion is a very common numeric value associated with planets, even used as one of the planetary orbital elements. ...
2
votes
3answers
294 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 ...
2
votes
0answers
286 views

Projectile motion equations @ very (!) high starting velocity

I've already searched Physics StackExchange for some similar question but I didn't find anything about this. Assumptions: Earth is a perfect sphere with it's core (X,Y,Z) -> (0,0,0) as a ...
2
votes
1answer
75 views

Single plane Ring system [duplicate]

Possible Duplicate: Why are our planets in the solar system all on the same disc/plane/layer? I've noticed this in many pictures, Planets are shown with a single ring around them (in some ...
1
vote
6answers
1k views

Can orbital energy be a source of perpetual power?

A thought just came to me, and I want to comfirm it here: If we figured out a way to harvest the energy from the orbit of the Moon, would that be perpetual? The Moon has been orbiting the earth for ...
1
vote
3answers
124 views

Angular momentum

The satellites are revolving around a planet in circular orbits by themselves (no external source to maintain their speed). Are we able to make them revolve in elliptical orbits by themselves? Do ...
1
vote
1answer
3k views

Why does the moon or the earth revolve anti-clockwise?

The question is very simple: Why does the moon or the earth or any another planet revolve anti-clockwise? And can any planet (or satellite) revolve clockwise? What is the physical law for this ...
1
vote
3answers
143 views

Rocket needed to send 100 gram of mass to outer space? [closed]

What kind of rocket would be needed to send 100 gr of mass to outer space? The mass can be moulded in any shape, but it would need not raise above 40 °C of temperature during the ...
1
vote
1answer
281 views
1
vote
1answer
135 views

Is it possible for a solar system to have planets orbiting the star(s) in a spherical pattern?

By the question I mean that the planets spin in their ellipse but all ellipses describe the surface of a near-sphere shape around a star. Same question but for a solar system with 2 stars of ...
1
vote
5answers
192 views

Satellite Collision Problem

I'm stuck on a problem of two satellites going towards each other. The mass of the first satellite is 400kg and the mass of the second satellite is 100kg. The altitude of the satellites is 1000km. I ...
1
vote
2answers
90 views

On constancy of cometary orbits

how are the comets able to keep to a nearly fixed orbital period, though they lose a certain amount of mass during their perihelion?
1
vote
2answers
2k views

Why an object travels a circular path?

It might sound stupid but seriously I couldn't find why? We have a mass with a constant speed, which is acted on by a unit force which is always at right angles to its direction of motion. Why do ...
1
vote
3answers
68 views

In Orbital Mechanics what is the quantity described below called?

I seem to recall that $r^2 \dot{\theta}$ is a conserved quantity in orbital mechanics, which I just proved using the Euler-Lagrange equations. Namely via: $ \mathcal{L} = \frac{m}{2} (\dot{r}^2+r^2 ...
1
vote
2answers
228 views

What's the weight of the earth?

What's the weight of the earth? That is, what's the weight of the earth in the gravitational field of the sun? I imagine it's either $0$, because there's no net fall toward the sun, so the downward ...
1
vote
2answers
47 views

Calculating the velocity of an elliptical orbit

I need an explanation as to why my solution to this problem doesn't work (please do not give me an answer or tell me exactly how to do it as this is a homework question that I need to do myself, hints ...
1
vote
1answer
357 views

How fast must a torus spin to have a felt gravity? [closed]

Given a rotating torus (like a gyroscope or a rotary) with a radius of 1km, how fast must it rotate to have someone inside the torus feel normal gravity of 1G?
1
vote
3answers
182 views

A satellite in orbit fires it's engines for a short interval. Is the new orbit closer or further away?

A satellite is in a circular orbit when its engines turn on to exert a small force in the direction of the velocity for a short time interval. Is the new orbit further or closer to the Earth? The ...
1
vote
3answers
369 views

Accelerating towards the center of your orbit

If you are in a perfectly circular orbit and accelerate perpendicular to your velocity (directly towards the center of the orbit), what would happen to your orbit? Would it just shift in the direction ...
1
vote
3answers
49 views

The orbit of 2010 TK7

Having just heard about the asteroid 2010 TK7 in Trojan asteroid seen in Earth's orbit by Wise telescope, I want to know more about its orbit. The BBC article says it moves above and below the ...
1
vote
2answers
759 views

Semi-major axis and ellipticity of a binary system?

In the image below (source at bottom), it seems to be suggesting that \begin{equation} a = a_{1} + a_{2}, \hspace{8cm}(1) \end{equation} where $a_{1}$ and $a_{2}$ are the semi-major axis of the ...
1
vote
2answers
4k views

What is geostationary orbit radius?

I'm asking this apparently "general reference" question for the simple reason: I was unable to find whether the quoted everywhere "35,786 kilometers (22,236 mi) above the Earth's equator" means ...
1
vote
2answers
156 views

Will Pluto be in the ecliptic plane when New Horizons passes by? Was this deliberate?

From the illustrations at the New Horizons website it seems that Pluto may be in or near the ecliptic plane when New Horizons passes by. Is this intentional? Of course Pluto was to move to that ...
1
vote
2answers
153 views

Could a really tall tube suck garbage in to space?

When I was around 10 years old, I had this idea that was supposed to solve our waste problems; I imagined having tubes miles high that would stretch in to space. Every tube would have a door at the ...
1
vote
2answers
59 views

Centrifuge speed of an object higher than a stationary orbit

In the question At what altitude above equator do gravitational and centrifugal forces cancel each other?, I asked how high a tower on the equator has to be such that at its top, gravitational and ...
1
vote
1answer
53 views

How does acceleration affect the orbit?

I want to know what roughly happens if we hit an orbiting body a little. And how is it possible that most of the objects have seemingly circular orbits around. How do they stabilize? I ask because it ...
1
vote
1answer
503 views

True or false: the Moon was touching the Earth 1.2 billion years ago

A creationist website makes this argument for the 6,000 year old earth. I'm embarrassed to say I don't know how to do the math to evaluate the claim myself. However, the time scales involved seems ...
1
vote
2answers
178 views

What are the correct initial conditions for the moon (in a simulation)?

So I've modeled the interactions between the sun and all the planets (and the interactions between the planets) using Verlet integration. I've used data from Wikipedia for masses, distance from the ...
1
vote
3answers
237 views

Gravity on the International Space Station - General Relativity perspective

My question is an extension to this one: Gravity on the International Space Station. If all the outside views of the ISS was sealed, then the crew inside would not be able to tell whether they were ...
1
vote
2answers
41 views

Why do “mascons” perturb orbits?

If the moon is a rigid body, why do the mass concentrations on the moon make orbits unstable? Doesn't a satellite just orbit the center of mass of it's parent body? Satellites (e.g. GRACE) seem to ...
1
vote
1answer
157 views

The circumference of the Moon's orbit around the sun?

I know that it orbits the sun in what looks like a 12 sided polygon with rounded corners. But I can't seem to find the radius/circumference anywhere.
1
vote
3answers
294 views

If there's no atmosphere in space shielding from particles, why is not dangerous for spaceships/humans?

Some time ago I was thinking about this. We know that space is almost matter-free, and also is plenty of particles and objects orbiting around all planets and sattellites. If objects orbit around ...