The orbital-motion tag has no wiki summary.
6
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1answer
603 views
What happened to Apollo's Saturn-third-stage rockets?
I read recently the original Apollo 11 press release and it mentions that the Saturn V's third stage (used for Trans-Lunar Injection) was deployed into a solar orbit of some kind:
I know that on ...
1
vote
1answer
119 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 ...
7
votes
1answer
243 views
Is there a “map” of the interplanetary transport network?
To my understanding, the idea behind the interplanetary transport network is that areas near heavy objects and their Lagrange points are accesible with comparatively little energy, for example one ...
1
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2answers
111 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 ...
3
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2answers
105 views
Cannon on spacecraft: hitting yourself
Some Soviet space stations reportedly had anti-aircraft cannons installed. Could such a cannon hit the firing space station accidentally on a subsequent orbit? The muzzle velocity of the cannon is ...
2
votes
1answer
59 views
Sunrise time across the globe?
This question is more astronomy related, I started thinking when I heard from one of my friends living in Jiamusi, that Sun rise at 02:00 and sets at 14:00, I know that this place is more near to ...
5
votes
2answers
409 views
Might a planet perform figure-8 orbits around two stars?
Might a planet perform figure-8 orbits around two stars?
I'm thinking that if the two stars were equal mass (and not orbiting each other) then a planet that were to go right between them would ...
2
votes
3answers
189 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
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2answers
514 views
Why is the center-of-mass of 2 bodies at the focus of their elliptical orbits?
Why is the center-of-mass of 2 bodies (which interact only via Newtonian gravity) located at a focus of each of the elliptical orbits?
I know that when there are no external forces, the center of ...
1
vote
1answer
76 views
What's the amount of deviation of cellestial orbits from perfect ellipses
It's well known that the planets don't orbit the sun in perfect circles and the characteristics of the elliptical orbits which serve as better approximations to their motion have been calculated ...
0
votes
1answer
128 views
How does Lunar Orbit Injection work?
Just what the title states.
I read that LOI was used by the Apollo program (and possibly others) to achieve escape velocity. How does it work? Is it merely a matter of centrifugal/centripetal force?
19
votes
1answer
733 views
Why does it take so long to get to the ISS?
I don't understand why when first launched Space X's Dragon capsule had to orbit the Earth many times in order to match up with the ISS? Was this purely to match it's speed, or to get closer (as in ...
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0answers
231 views
How to find orbital radius of star in a binary system using redshift and orbital period data? [duplicate]
Possible Duplicate:
About binary stars and calculating velocity, period and radius of their orbit
I am given the non-redshifted wavelength of the EM radiation from one of the stars, the ...
0
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2answers
83 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?
8
votes
1answer
157 views
Orbit through L4 and L5
I was reading the Wikipedia article on Lagrangian points and doing the requisite wiki walk through the various quasi-satellites of Earth when a question occurred to me:
Could there be a stable or ...
9
votes
1answer
286 views
Apollo and orbital mechanics: orbital decay if the Trans Earth Injection (TEI) burn had failed
I'm reading Jim Lovell (Apollo 8 and 13) and Jeffrey Kluger's book Apollo 13, which is a fantastic read about a long past era I only have kindergarten memories of. On page 54 there is a paragraph that ...
1
vote
1answer
88 views
More efficient far-future means of keeping the earth alive? [closed]
In about 7 Billion years our planed will be consumed by the ever-growing sun, life would have become extinct long before that. That means that in several hundred thousand years we have a deadline to ...
6
votes
2answers
142 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 ...
4
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2answers
351 views
What's the reason for the seasons?
In the diagram, it shows that the fundamental reason for different seasons is when the northern hemisphere is titled towards the sun there's summer in northern hemisphere and winter in southern ...
0
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1answer
77 views
A Satellite's Perspective
If a planet is spinning east to west and there is a satellite spinning from west to east...
Can the satellite travel at a speed sufficient to make the planet appear, from the vantage point of the ...
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vote
3answers
106 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 ...
0
votes
1answer
108 views
What would be the path of the earth seen by the astronaut in the lunar sky? [closed]
An astronaut camps on the moon for a period of one month as per the earth’s calendar.
What would be the path of the earth seen by the astronaut in the lunar sky?
(A) The earth remains approximately ...
0
votes
2answers
233 views
Calculating eccentricity from semi-major axis, position and velocity of particles
I'm trying to calculate the eccentricity of a binary system's body knowing the bodies' velocities, positions, masses and the semi-major axis. I am only trying to calculate the eccentricity for one of ...
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0answers
371 views
Calculating semi-major axis of binary stars from velocity, position and mass
I'm trying to calculate the 'instantaneous' semi-major axis of a binary system with two equal (known) mass stars for an $N$-body simulation. I know their velocities and positions at a given time, but ...
1
vote
3answers
539 views
Work Done by Rockets in Orbital Motion
A weather satellite ($m_s = 4350$ kg) is in a stable circular orbit around the Earth ($m_E = 5.97 \cdot 10^{24}$ kg). It completes an orbit once every 2 and a half hours.
(I'm sure about these 2 ...
3
votes
1answer
371 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
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4answers
643 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 ...
0
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1answer
111 views
How to find the orbit of a moving point object given 3 past passing positions?
How do I find the orbit of a moving point object given 3 past passing positions and the tangents at these passing positions, and given that the orbit is known to be an ellipse?
3
votes
1answer
274 views
Radial fall in a Newtonian gravitational field [duplicate]
Suppose an object of mass $m$ starts at rest at a radial distance $ r_0$ from a perfectly spherical mass $M$ (where $m << M$), $r_0 > R =$ radius of $M$.
Can we analytically determine when ...
2
votes
1answer
544 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 ...
18
votes
3answers
622 views
Why do the planets' orbital distances fall on an exponential curve?
Background: I was recently reading a book on the planets to my son and I noticed a pattern in the distributions of the planets. The planets' distances roughly follow an exponential distribution.
...
16
votes
4answers
1k views
What symmetry causes the Runge-Lenz vector to be conserved?
Noether's theorem relates symmetries to conserved quantities. For a central potential $V \propto \frac{1}{r}$, the Laplace-Runge-Lenz vector is conserved. What is the symmetry associated with the ...
3
votes
1answer
235 views
How do I calculate the time it would take for a space craft launching from earth to reach another planet?
I am making a matlab program the my final project for my programming class in college. I have chosen this problem, but I am bashing my head against the wall trying to figure out the equations and how ...
0
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0answers
106 views
How long until “final totality”? [closed]
It is given that the angular size of the Sun as viewed from Earth is $0.533^\circ$, the distance of the Moon from Earth at perigee is $3.633\times 10^5$ km, and the mean radius of the Moon is $1737.1$ ...
3
votes
1answer
166 views
Know altitude and speed of an object in orbit, with true anomaly
I'm quite stuck with this problem.
I know that I have an object in orbit. I know the eccentricity of that orbit, as well as the semi-major axis of the orbit.
Giving a true anomaly, how do I find ...
2
votes
2answers
487 views
Orbital radius of Geo-stationary satellite
Could you please tell, Why all the geo-stationary satellites are to be dropped at same height from earth? Why can't it be closer or away from its regular orbit(ie, 35,000 km)? If all satellites are ...
4
votes
1answer
319 views
How does an object falling into a plain Schwarschild black hole appear from near the black hole?
I know that when viewed from infinity (or from a very large distance from the black hole event horizon), an object that falls into the black hole will appear to slow down and will become more and more ...
2
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3answers
680 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
3answers
151 views
Tidal acceleration for a retrograde rotation?
Consider two nonelastic spherical bodies with uniformly distributed density, a small such body in a circular orbit around the bigger one.
And consider the smaller body's rotation is matched (as if ...
15
votes
2answers
136 views
Why don't stars in globular clusters all orbit in the same plane?
Globular clusters like Omega Centauri certainly don't seem to be very coplanar at all.
In other words, why doesn't the explanation at Why are our planets in the solar system all on the same ...
6
votes
3answers
171 views
“Reverse engineering” of a horoscope?
I'll start with a disclaimer -- this is not a question about astrology itself, I'm neither trying to refute nor to defend astrology. I'm interested in purely technical things, which are mostly ...
6
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7answers
2k views
How does the earth move?
My son who is 5 years old is asking me a question about how the earth moves around the sun. What answer should I give him?
3
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2answers
47 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 ...
0
votes
1answer
171 views
What are the known relationships between rotation of planets/moons and their distance to Sun?
What are the known relationships between rotation of planets/moons and their distance to Sun? Or any other known attributes? For example, the sidereal year for planets is directly related to their ...
13
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5answers
3k views
Why do we always see the same side of the Moon?
I am puzzled why we always see the same side of the Moon even though it is rotating around its own axis apart from revolving around the earth. Shouldn't this only be possible if the Moon is not ...
3
votes
4answers
561 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 ...
28
votes
1answer
501 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
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1answer
368 views
How does the view of night sky change as the Sun orbits around the Milky Way?
I know that the Sun and hence the Solar System orbits around the galactic center of the Milky Way. Does this rotation cause any visible change in the night sky?
I know that human life span is ...
6
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3answers
1k views
What is the irregularity in Uranus' orbit that is caused by Neptune?
I carefully read the Wikipedia article Discovery of Neptune, and I don't get what the irregularity of Uranus orbit was that lead to the discovery of Neptune. Years ago, I watched some educational film ...
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3answers
26 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 ...
