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

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233 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 ...
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3answers
235 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 ...
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3answers
2k views

Uniform Circular Motion

Why does the object not go inward, into the circle if the acceleration is inward? I think its because the velocity to outward? So they sort of cancel each other out? But if the speed is kept ...
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1answer
332 views

What is the pause called at the apex of an object's trajectory?

My apologies for such a basic question--I am a musician, not a physicist. But I cannot anywhere find the word, if one exists, that describes that elegant pause of an object such as a ball, thrown ...
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1answer
158 views

What are “cycles of anomaly” and “cycles of longitude”?

In several early (pre-1600) astronomical texts I read about "cycles of anomaly" and "cycles of longitude", but it us unclear to me what these terms mean. They were clearly familiar to authors at the ...
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1answer
368 views

What path would advanced spaceships take to move between planets? [closed]

Right now, space travel is all about carefully moving between orbits. If you want to go from Earth to Mars, you wait until the two planets are correctly aligned, and then place yourself into an ...
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0answers
132 views

What is the angular distance between Ptolemaic perigees of Mercury?

In his excellent treatment of the history of the science of astronomical distances and sizes, Albert van Helden says (p.29) that The complicated [Ptolemaic] model of Mercury has the curious ...
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1answer
247 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 ...
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1answer
826 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 ...
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1answer
342 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
1k 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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56 views

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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197 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 ...
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1answer
646 views

When and how were relative distances to the planets first measured?

I understand that the absolute distance to a planet can be measured using earth-baseline (e.g., diurnal) parallax, and that the first reasonably accurate such measurement was made for Mars by Cassini ...
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4answers
2k 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 ...
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2answers
491 views

Was Jupiter's mass “guessed at” by Kepler or Galileo?

Following Kepler's publication of his 3rd law of planetary motion1, $$p^2 / r^3 = 1$$ in 1619, it would have been possible to use telescopic observations to arrive at an estimate of the orbital ...
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2answers
971 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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1answer
76 views

Why no image of the North or the South Pole Weather? [closed]

I was watching a youtube video which refers to National Geographic and other metereological sources that the US govenrment has banned access to the weather and metereological data of both Poles. What ...
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2answers
560 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 ...
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2answers
1k views

Does effective potential for a gravitational force have a maximum below $E=0$?

The relevant figure is below (taken from Goldstein's Classical Mechanics). This figure plots the effective potential for a gravitational force. Does the effective potential $V'$ go flat below $E_2=0$? ...
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1answer
268 views

Do Lagrangian points actually maintain a fixed distance?

I was reading on up Lagrangian points and the restricted three-body problem. From what I was able to tell, the Lagrangian points are 5 points in a two-body system such that a third body would be ...
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1answer
503 views

Condition for circular orbit

I am a little confused about the condition for circular orbit. Goldstein's Classical Mechanics has the condition for circular orbit as $$f'=0\tag1$$ where $f'$ is the effective force. I understand ...
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2answers
428 views

Energy required to kick a planet orbiting the Sun from an elliptical to a parabolic path

I am trying to solve the following problem from Goldstein's Classical Mechanics: A planet of mass $M$ is in orbit of eccentricity $e=1-\alpha$ where $\alpha<<1$, about the Sun. Assume that the ...
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2answers
303 views

Why is there this asymmetry between the two foci of an orbital ellipse?

Why does the Earth revolve with the Sun at one of its foci? Does the other focus do nothing? Why is there this asymmetry in our solar system?
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3answers
2k views

What is the difference between a bounded orbit and a closed orbit?

Goldstein's Classical Mechanics has a puzzling few sentences in his discussion of orbits. Referring to the case of orbit where the energy is low enough for the orbit to be bounded, he says :"This ...
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3answers
487 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 ...
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1answer
156 views

Cyclic co-ordinates implying the constant velocity motion of center of mass of a system of particles

I'm reading the section on Central Force in my textbook (Goldstein's Classical Mechanics has a similar argument in the chapter titled "The Central Force Problem", first section), where we have the ...
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1answer
2k 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: (Source: Press ...
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1answer
161 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 ...
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1answer
2k 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 ...
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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 ...
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2answers
111 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 ...
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1answer
73 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 ...
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4k 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 ...
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3answers
297 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 ...
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2answers
215 views

Can a large thermonuclear bomb be used for planetary defence?

How effective would a thermonuclear device of 47 megatons or higher like the zsar bomba be in space? Could we use as planetary defence on somthing like an asteroid as long as it is detected in time ...
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6answers
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Gravity on the International Space Station

We created a table in my physics class which contained the strength of gravity on different planet and objects in space. At altitude 0(earth), the gravitational strength is 100%. On the moon at ...
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2answers
1k 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 ...
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1answer
139 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 ...
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1answer
672 views

How does Lunar Orbit Injection (LOI) 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?
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625 views

Is the escape velocity at Geosynchronous Earth Orbit 0km/hr?

Follow-up question to How long must escape velocity be maintained? Is the escape velocity at GSO 0?
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1answer
86 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?
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1answer
338 views

Does a tidally locked planet have seasons?

Could a tidally locked planet have seasons? According to my understanding, a tidally locked planet rotates around itself exactly once per rotation around its sun. However, if the axis of rotation of ...
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1answer
1k 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 ...
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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?
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1answer
204 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 ...
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1answer
584 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 ...
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3answers
228 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, ...
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1answer
103 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 ...