The orbits tag has no wiki summary.
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2answers
58 views
Can the axis of rotation of a celestial body point in any arbitrary direction?
I am developing a small computer program that involves moderately simple simulation of elliptical Kepler orbits for fictional, generated star systems. I'm doing this without much prior knowledge of ...
2
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2answers
65 views
Does spin of the earth vary at different locations?
Does the spin of the earth around its axis vary at different distance from the sun?,if so how does it correspond to the length of day and night,?
4
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2answers
92 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, ...
7
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2answers
170 views
No closed orbits for a Newtonian gravitational field in 4 spatial dimensions
We are supposed to show that orbits in 4D are not closed.
Therefore I derived a Lagrangian in hyperspherical coordinates
$$L=\frac{m}{2}(\dot{r}^2+\sin^2(\gamma)(\sin^2(\theta)r^2 \dot{\phi}^2+r^2 ...
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0answers
23 views
Verlet Leap-fog Method of approximating orbits [migrated]
I found the following simulation of an orbit given the semi-major axis of the ellipse, eccentricity, initial velocity, the mass of the object being orbited, and initial position of the orbiting ...
12
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2answers
197 views
Does an elliptical orbit of a satellite maintain its orientation as the Earth revolves?
Imagine a satellite in an elliptical orbit around Earth. As the earth travels around the sun, does the elliptical orbit of the satellite swing around Earth, as pictured in A, or does it maintain a ...
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1answer
38 views
How to find distance of closest approach for a Schwarzschild geodesic?
What is the distance of closest approach in this Wikipedia article?
I can't seem to find its definition, and this other question doesn't have an answer I can understand.
2
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1answer
71 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
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1answer
73 views
Earth and Moon computer simulation [closed]
So I want to simulate the solar system but want to start simple with one orbiting body.
However, I never did anything like this before and was wondering if anyone here could give me some hints.
...
1
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1answer
59 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
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1answer
55 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 ...
3
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1answer
53 views
Uniqueness and existence of polygonal orbits through a spherical shell
Say we have a spherical wire mesh raised to a negative voltage. Then let's say we release a proton from near the surface, and away from the surface, at some angle and speed. Also, imagine that the ...
4
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1answer
77 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 ...
1
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2answers
151 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
1answer
86 views
How do you actually define an orbit?
How do you actually define an orbit?
I believe, Newtonian Mechanics describes an orbit as one object in free fall around another where projectile paths become elliptical. I think, Einstein describes ...
4
votes
1answer
92 views
(Re-)use of a space elevator (basic mechanics and potential energy source)
It's said that if a space elevator were made then it would be much more efficient to put objects in orbit. I've always wondered about the durability of a space elevator though. I don't mean the ...
5
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1answer
81 views
How is celestial navigation done on a low-level?
When we send a probe off to Jupiter or Saturn, or even Earth orbit, how are the rocket firings timed and coordinated?
For instance, when I want to drive to another city I pull onto the highway and ...
7
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3answers
252 views
How do you explain Kepler's third law in general terms without complex math?
I understand the first law-elliptical orbits, and the second-equal area in same time, but I need help with the third one. Note that I am not in an AP course or taking calculus at the moment so simple ...
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2answers
685 views
What is the limit to how many satellites can orbit the earth?
I would like to know how many satellites are physically able to be in place, at the same time, orbiting the earth. Lets ignore which Nations need or use the most satellites (area in space above them) ...
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4answers
90 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 ...
1
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3answers
97 views
Condition for closed orbit [closed]
I'd like to know when an orbit is closed. I know that, to have a closed orbit, there is a ratio that must be a rational number, but I don't know other things..
0
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2answers
89 views
How is space ship's acceleration perceived if the acceleration is perpendicular to the velocity?
Spacecraft in orbit around the Earth are constantly accelerated by the gravitational field of Earth. That's why the spacecraft ($m \ll M$) is in an (elliptical) orbit around the centre of gravity of ...
2
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1answer
129 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 ...
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2answers
167 views
Expression for distance of closest approach in Schwarzschild Geodesics
The Wikipedia article Two-body problem in General Relativity uses two length-scale variables, $a$ and $b$, to simplify the math. For some information about these, consider these statements from the ...
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6answers
2k views
Could there be a star orbiting around a planet?
I wonder if there ever could be a star (really small) which may orbit around a planet (really big)?
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2answers
87 views
Does Planet revolution time is always greater the more it's getting away from the center?
The entire question is in the title .
It's the case for the solar system but is it always the case ? Can a planet do a revolution faster than another that is closer to the center ?
As far as I ...
4
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2answers
226 views
How to calculate linar velocity of planet orbit?
I try to simulate a solar system with planets (with random mass) placed randomly around a sun with a mass $X \times \text{solar mass}$.
The simulation is going well when I use real data ...
9
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3answers
511 views
Gravity in other dimensions than 3 and stable orbits
I have heard from here that stable orbits (ones that require a large amount of force to push it significantly out of it's elliptical path) can only exist in a three spatial dimensions because gravity ...
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2answers
274 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 ...
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0answers
40 views
Length of the orbit (semiclassical orbits)
The Gutzwiller trace is about
$$ d(E)=d_{0} (E)+ \sum_{p.o}A_{p}Cos(S(E)l_{p}) $$
and $ l_{p} $ are the length of the orbit
However my question is, how can one derive the length of the orbit from ...
5
votes
1answer
154 views
Finding interplanetary flight trajectory using calculus of variations?
Consider two orbits $x(t),\space y(t)$ representing the origin and destination for some spaceflight of interest. These could be, for example, cycloids describing LEO and another orbit circling, say, ...
5
votes
1answer
92 views
Convert latitude of lowest altitude to argument of perigee?
I am designing an orbit around Mercury. I know the values I want for the semi-major axis, eccentricity, inclination, and RAAN. I want the altitude of closest approach (periapse) to occur at ...
5
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4answers
330 views
Are galactic stars spiraling inwards?
Are the stars in our galaxy spiraling inwards towards the center, or are they in a permanent orbit?
And if we are heading towards the center then what is the rate of this process?
I started ...
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2answers
228 views
What happens to orbits at small radii in general relativity?
I know that (most) elliptic orbits precess due to the math of general relativity, like this:
source: http://en.wikipedia.org/wiki/Two-body_problem_in_general_relativity
I also know that something ...
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5answers
2k 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 ...
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1answer
80 views
What is the orbital motion where both foci are located at one point?
What is the orbital motion where both foci are located at one point? I know that an ellipse orbit is motion with two distinct foci.
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1answer
178 views
Result of increasing the radius of earth?
How can increasing the radius of earth may cause an impact on the solar system ? Like, would earth may start making a bigger orbit (due to increase in size and wait) or vice versa ? or else ?
PS: The ...
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1answer
485 views
James Webb Space Telescope's halo orbit at Lagrange point L2
The James Webb Space Telescope (JWST) is expected to be launched in 2018 and operate in the L2 vicinity, about 1.5 million km from Earth.
It will be placed in a halo orbit around the unstable L2 ...
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1answer
131 views
Is there a simple, accurate formula for calculating transit times from rise and set times?
I have access to "rise" and "set" times for astronomical objects, and want to determine the corresponding times of culmination. Is there a reliable and accurate way to do this? It isn't clear to me ...
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1answer
572 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 ...
0
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1answer
79 views
Is Earth's orbit altered by recoil from take-off/launch/recovery of aero/space vehicles?
Just what the title states.
Pretty much all movement on Earth is by pushing against the much greater mass of Earth. Given there are easily thousands of aircraft taking flight/landing, and a lesser ...
1
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1answer
108 views
How closely may an artificial satellite orbit Earth without decaying appreciably each orbit?
Just what the title states.
An artificial satellite will orbit Earth with some defined angular momentum.
An aircraft,on the other hand, relies upon it's engines to provide continuous forward velocity ...
3
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1answer
139 views
Earth-Moon orbiting each other after being engulfed by Red Giant
Recently some exoplanets were discovered which are thought to be the leftover cores of giant planets that had survived a star becoming a Red Giant and then shrinking back to a subdwarf.
If giant ...
2
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1answer
242 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
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1answer
196 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 ...
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2answers
553 views
Would a rocket burn more fuel to get from Earth's surface to LEO, or to get from LEO to GEO?
Would a rocket burn more fuel to get from Earth's surface to Low Earth Orbit, or to get from LEO to Geosynchronous Earth Orbit?
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0answers
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Would ferromagnetic space debris have been magnetized by their orbit in the Earth's magnetosphere?
Given a nail, and a magnet it is possible to magnetize the nail by patiently rubbing the nail until it is magnetized; albeit the field strength may be less than that of the source.
With several ...
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3answers
709 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 ...
2
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2answers
391 views
What the difference between “orbital” and “orbit”?
What's the difference between "ortibal" and "orbit"?
Which one should be used in physics?
In quantum mechanics, is "atomic orbital" or "atomic orbit" used?
And what about in classical mechanics? A ...
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4answers
2k views
Why do covalent bonds form?
why in a covalent bond are "the bonded electrons are in a lower energy state than if the individual atoms held them at the same proximity"?
Also is it correct that " I think when you start pushing ...
