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

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2answers
65 views

Towing of asteroid

I recently studied that NASA has planned to tow and place it in the orbit of the moon. My doubt is when asteroid is placed in the orbit near moon.since the gravitational field of earth is very ...
1
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2answers
163 views

Saturn ring stabilization

The rings of Saturn are the most extensive planetary ring system of any planet in the Solar System. I'm wondering, what power is primarily responsible for that stability? © Public Image by NASA ...
5
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2answers
351 views

Gravitational potential outside Lagrangian points or Lagrange points

The diagram in Why are L4 and L5 lagrangian points stable? shows that the gravitational potential decreases outside the ring of Lagrange points — this image shows it even more clearly: If I ...
4
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2answers
176 views

Runge-Lenz vector and Keplerian Orbits

Is the loss of closed Keplerian orbits in relativistic mechanics directly tied to the absence of the Runge-Lenz vector?
0
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1answer
103 views

What Speed Would an object need to leave the earth at to reach L1? [closed]

Let's say the Earth is an airless sphere. What speed would an object weighing 1 kg need to leave the surface at in order to get to and be motionless at L1, where the Moon's gravity becomes stronger ...
1
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1answer
167 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
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1answer
164 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 ...
11
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4answers
2k views

Is Feynman's explanation of how the moon stays in orbit wrong?

Yesterday, I understood what it means to say that the moon is constantly falling (from a lecture by Richard Feynman). In the picture below there is the moon in green which is orbiting the earth in ...
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1answer
100 views

Simulating an orbit, primary is not at focus

I've been toying around with some -very- simple orbital simulators, mostly using preexisting physics libraries (I took a layman's stab at doing it with vectors too). The thing that is confusing me is ...
2
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1answer
200 views

Motion of mercury [duplicate]

I studied that mercury motion around the sun slightly displace by a certain value in each year. But, this is not predicted by kepler until general theory of relativity. What does general theory does ...
-1
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2answers
275 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 ...
5
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1answer
108 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 ...
8
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3answers
546 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 ...
2
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2answers
159 views

Generalised Kepler's III law?

I have derived the following equation for the time-derivative of the angle that an orbiting particle subtends with one of the coordinate axes, with the other particle at the origin (this is the focus ...
4
votes
1answer
439 views

How is the equation of motion on an ellipse derived?

I would like to show that a particle orbiting another will follow the trajectory \begin{equation} r = \frac{a(1-e^2)}{1 + e \cos(\theta)}. \end{equation} I would like to do this with minimal ...
-1
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2answers
3k 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) ...
2
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4answers
144 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 ...
2
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3answers
207 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..
2
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1answer
685 views

How can a satellite's speed decrease without its orbital angular momentum changing?

I have no idea what the answer is. I'm supposed to answer it within 3-4 sentences.
0
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3answers
123 views

Stresses in asteroid during close flyby

The acceleration of an asteroid (such as 2012DA14) as it approaches earth is proportional to the reciprocal of distance $r$ from earth center, squared. the derivative of the acceleration, or jerk, is ...
2
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2answers
123 views

Shoot object into the Sun using minimal energy

Say I want to shoot a cannonball into the Sun with minimal energy (minimal initial velocity relative to Earth). In which direction do I shoot it? Let's neglect Earth's gravity, if that would make ...
0
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2answers
181 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
votes
1answer
228 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 ...
0
votes
1answer
158 views

Lagrange L4 L5 points and perifocal plane

I have 2 satellites at the L4 and L5 points and these are watching an object. Each satellite provides the angle to the object from its own position from a line parallel to the $\text{x-axis}$ of ...
7
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3answers
254 views

Falling through the rotating Earth

Suppose you were standing on the rotating Earth (not necessarily Equator or the poles) and suddenly your body lost the ability to avoid effortlessly passing through solid rock. Because the earth's ...
2
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2answers
399 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 ...
22
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6answers
4k 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)?
2
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2answers
135 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
votes
2answers
972 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 ...
0
votes
2answers
180 views

Planet's Moon attrated by sun [closed]

I'm currently writing a code to generate solar system and $N$ number of planets / moons. I use real data to test (earth / sun / moon data). I succeeded in placing the earth and make it orbit around ...
2
votes
1answer
413 views

Finding orbital eccentricity

I have this problem: They give me, from a satellite that is in orbit in earth, a value for the period, and the closest height to earth surface, the ask me what the eccentricty of the orbit is. I have ...
0
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1answer
2k views

Energy in orbit of satellites around the earth lost?

If the total mechanical energy in a satellite's orbit (assuming circular) is greater when it is closer to the earth, and hence smaller when it is farther from the earth, then we can say that as the ...
0
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2answers
201 views

Two moons of Earth?

Hypothetically, suppose there is a situation where the Earth's moon gets neatly sliced into two equal hemispheres, and the force responsible for this slicing also creates a distance between the two ...
9
votes
3answers
2k 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 ...
5
votes
1answer
339 views

Can you tell just from its gravity whether the Moon is above or below you?

If you are on a place of Earth where the Moon is currently directly above or directly below you, you experience a slightly reduced gravitational acceleration because of Moon's gravity. This is what ...
9
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3answers
383 views

Is the gravitational potential of a planet in orbit always equal to minus the squared velocity?

Say a planet (mass $m$) is orbiting a star (mass $M$) in a perfect circle, so it is in circular motion. $F=ma$ and the gravitational force between two masses $F=\frac{GMm}{r^2}$ so ...
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2answers
2k 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 ...
3
votes
1answer
384 views

Where does energy for high and low tides come from?

High and low tides are caused by Moon gravity attracting water. Now there's friction, waves cause erosion, their energy is used in power plants yet the tides work for millions of years and are ...
4
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3answers
216 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 ...
4
votes
3answers
602 views

Does Kepler's law only apply to planets?

Does Kepler's law only apply to planets? If so why doesn't it apply to other objects undergoing circular motion? By Kepler's law I'm referring to $T^2 \propto r^3$
3
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2answers
381 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?
3
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4answers
876 views

Angular momentum power plant on Earth

If tidal power plants are slowing down Earth's rotation then is it theoretically possible to build a power plant that would drain energy from Earth's angular momentum (thus slowing down it's ...
5
votes
1answer
369 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, ...
9
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3answers
280 views

Can an orbit be calculated using two points and transit time?

Working in only two dimensions and assuming that the central body is at the origin of the coordinate system, given two points in space and knowing the transit time between those points, as well as the ...
5
votes
1answer
184 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
votes
4answers
447 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 ...
3
votes
2answers
663 views

When is the right ascension of the mean sun 0?

I understand that the right ascension of the mean sun changes (at least over a specified period) by a constant rate, but where is it zero? I had naively assumed that it would be zero at the most ...
2
votes
2answers
241 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. ...
7
votes
2answers
543 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 ...
48
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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 ...