# Tag Info

### Why is the L3 Lagrangian point not perfectly stable? And why is the Earth-Sun L3 point a bit less than one A.U.?

L1, L2 and L3 are saddle points in the effective potential of the gravitational field in a rotating frame of reference. That is if you combine gravity (of Earth and Sun) with the centrifugal force on ...
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### How do Lagrange points L2 and L3 form?

According to my understanding Lagrange points L1, L4 and L5 can form because gravitation pull can cancel out here as these are between Sun and Earth (where gravitational pull is in two different ...
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### Why is the L1 point (Lagrange) almost 1 million miles from Earth? Shouldn't it be closer to us?

If you divide 333,000 by 10,000, you get 33.3, meaning the Sun should be yanking on an object placed at L1 with more than thirty times the force as the Earth is.... That's not how the Lagrange points ...
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### Will JWST be as durable as the hubble telescope?

Hubble was in low earth orbit, and was always intended to be serviceable. In fact, the original plan for Hubble was to have the space shuttle carry it down from orbit and take it back up, but they ...
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### Why don't we find planetoids at L4/L5?

In astronomy, a trojan is a small celestial body (mostly asteroids) that shares the orbit of a larger one, remaining in a stable orbit approximately 60° ahead of or behind the main body near one of ...
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### Do Pluto and Charon have unusual Lagrange points?

The L1, L2, and L3 points are unstable in any orbital system. (source) The L4 and L5 points of a pair of bodies are only stable if the larger of the bodies is at least 25 times as massive than the ...
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### Is possible to identify the Lagrange L2 point in the sky from the earth?

Stargazer's rough, quick method: Look at the sky at local solar midnight, halfway between sunset and sunrise. Locate the ecliptic. If you're a stargazer, you should know where that is: it's the line ...
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### Is possible to identify the Lagrange L2 point in the sky from the earth?

To get the L2 position from Horizons, you need to ask it for "Apparent AZ & EL", which is quantity 4 in the Observer table custom settings. When setting the time span, you need to use ...
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### Is there a ceiling for stable L4 or L5 masses?

The Giant Impact Hypothesis, a theory of how the moon was created, says that once it exceeds 10% of the mass of your 'J', the orbit of an L4 or L5 (your 'T') destabilizes. Possible origin of Theia ...
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### Determining the area of Lagrange Points

My question: is there a way to determine the "stable" region in each Lagrange location? Particularly in the L4 and L5 regions. tl;dr: Yes but it's usually a fancy version of "trial and error". We ...
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### Could there be a planet at the barycenter between two or more stars revolving around each other?

No. Such an arrangement is at best "metastable". That is, although there are periodic solutions to the three body problem (stable orbits) an infintesimal perturbation (eg the proverbial ...
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### Why don't we find planetoids at L4/L5?

Moons formed in a number of ways. Many moons are just like the debris that is found at L4 and L5, of the nearly 80 known moons of Jupiter, most are small, irregular and are probably captured ...
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### Is possible to identify the Lagrange L2 point in the sky from the earth?

Running the JPL Horizons calculation as in the original question gives the RA and DEC of the L2 point: ...
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### Time in 0 gravity points

makes time pass more slowly for us This is a fundamental misunderstanding of time dilation which only says anything about the relative rates that clocks run compared to one that is in your own frame ...
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### Do the Sun's rays get focused at or near the L1 Lagrangian point?

The Sun's rays don't get focused, by the Earth, at L1. The Earth can act as a gravitational lens and it does have a focal length of 15,375 AU, more than five hundred times the distance to Neptune. ...
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### Fate of a planet orbiting a Lagrange point behind a star?

The stability of this system depends the ratio of masses of the two stars. If the larger star is more than 25 times more massive than the smaller star, then L5 is potentially stable, and this remains ...
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### Why is the L3 Lagrangian point not perfectly stable? And why is the Earth-Sun L3 point a bit less than one A.U.?

Why is the L3 Lagrangian point not perfectly stable? In the circular restricted three-body problem (CR3BP or CRTBP) an object at any of the first Lagrange points L1, L2, L3 is unstable mathematically....
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### Could the Moon placed near the Sun-Earth L1 point remain in a heliocentric 1:1 resonant orbit with Earth? If Earth were at 1 AU, where's the Moon?

Most discussions of Lagrange points use the simplification of the circular restricted three-body problem, where two objects (e.g., the Sun and the Earth) are massive and in fixed circular orbits about ...
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### Do any equivalent of Lagrange points exist between galaxies?

Short answer: likely sometimes. The gravitational potential of a galaxy is not going to be a spherically symmetric $1/r$ potential, since it is the sum of the potentials of all the stars, plus from a ...
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### Would an accumulation of dust in a planet's L1 Lagrange point plausibly obscure it from Earth?

No. The L1 point is unstable and dust doesn't accumulate there. A dust cloud could not be large and dense enough to obscure a planet without being so massive that it would contract under its own ...
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### L2 point ephemeris (celestial mechanics)

Bad news, this type of SPK file has a different sort of interpolation that is not supported by the jplephem package (Hermite interpolation vs Chebyshev polynomials)...
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### Is there a ceiling for stable L4 or L5 masses?

Note: Answering from a comment posted on Space Exploration The classical stability analysis of these libration points assumes that we are examining the motion of a particle whose dynamics are ...
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### L4 and L5 stability

It does indeed seem counterintuitive that $L_4$ and $L_5$ would be at the same time both high points of potential as well as stable points in the system. In fact, a quick look at an example contour ...
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### Would an object placed at L1 be seen in front of the Sun from Earth?

Objects are not place at the Sun-Earth L1 or L2 Lagrange points. They are instead placed in pseudo orbits about these points. These pseudo orbits intentionally avoid being directly in line with the ...
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### Lagrange points for bodies in elliptical orbits?

One of the answers to the researchgate question What are the equation of motion for elliptical restricted three body problem? says: https://www.sciencedirect.com/search?qs=equation%20of%20motion%...
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### Is there a Lagrange point between the earth and the moon?

Yes. The Earth-Moon system has a Lagrange point L1, positioned between the Earth and the Moon, It is about 85% of the distance to the moon (about 320000km compared to 380000km.) A body at L1 would ...
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### Does earth's Umbra reach Sun-Earth L2?

The Lagrangian point $L_2$ is very close to the most distant point from Earth with an umbra. $L_2$ is like the radius of the Hill sphere at $r=a\sqrt[3]{\frac{m}{3M}}$ for circular orbits, with $m$ ...
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### Why are telescopes positioned in Lagrange points?

tldr; L2 is a very stable thermal environment as well as good instantaneous sky visibility and high observing efficiency. The main reason space telescopes are placed in an L2 orbit is because L2 ...