What Are Lagrange Points? 

-Explains potentially confusing subject very well -Gives potential applications for literature and reality -Funny ending I love these videos!

As I watch this and at this very moment of these historic times, the James Webb Space Telescope (JWST) has successfully launched and completed the separation from Ariane 5! I appreciate the explanation of the Lagrange points in fine and simple terms.

The Mobile Suit Gundam series makes heavy use of the Lagrange points. The Earth/Luna Lagrange system has been colonized with O'Neill Cylinder style stations.

I would watch an unhealthy amount of an astrophysics channel run by Dan and Alasdair!

L3 is useful in sci fi to monitor the blind spot behind the sun. So that an enemy fleet can't 'come out of the sun' to attack earth. You would use 4 or 5 to bounce the signal to Earth.

The Lagrange Points are where most of the colonies "Sides" are in Gundam.

At the Langrange points humanity can be free, it's soul no longer held down by gravity. SIEG ZEON!

So what you're saying is we need to nuke L3 right now?

L4 and L5 look like good locations for resource gathering. With all 5 points in use it would make for a good early warning system and wide range communication system. L2 would make a great location for a ship yard.

You sir just allowed me to develop the space capabilities of my sci-fi civilisation, more notably its shipyards, space control and security satellites, observation and spy satellites, mega stations and so much more! Your work on Spacedock has allowed me to develop and enhance my sci-fi project on multiple occasion and for that, I want to say thank you very much!

I always wondered what L2 and L4/5 Earth stations in Mass Effect mean, now I know. Thanks Spacedock :)

"As soon as 2021, the James Webb Orbital Space Telescope is scheduled to be deployed..." *cries*

The was a PC game back in the 90s the utilized the lagrange points as FTL jump positions. Had something to do with needing to have no outside gravity interfering with the jump for it to work. I forget the game's name though (It has been a couple of decades :) ).

0:16 I thought you were gonna say Gundam tbqh.

4 and 5 seem like good places to set up asteroid harvesting stations

Respect. Planetes was a outstanding and super underrated anime.

Excellent Episode. To expand slightly for those interested in the importance of these free-body system points: L4 and L5 in both Earth-Sun and Earth-Moon configurations are perfect places for very large construction and habitat facilities not only because they make for easy transit from Earth, but also because shipments from other locations such as Ceres or 16 Psyche (believed to be a highly metallic protoplanet core) directed at these points could easily arrive with low energy trajectories without having to worry about endangering Earth, near-Earth-orbit facilities, Luna or Lunar orbit facilities with a potential misfire/missed trajectory insert by an automated system. This would allow us to theoretically transfer large amounts of materials from these other locations without requiring onsite personnel, instead sending automated mining systems and in-situ resource recovery systems to construct, harvest local fuel, and send material to the L4 and L5 points where their proximity to earth allow for near real-time telepresence oversight of complex construction tasks. Ceres, for example, has a very large water-ice content and has lots of rock and minerals suitable for constructing interior surface features of habitats such as O'Neill or McKendree Cylinders (habitable interior surface area roughly equal to Russia (13 million square kilometers), or even modified Standford Torus constructs. Meanwhile 16 Psyche's high metal content means we could build super structures for several billion O'Neill cylinders. If we use active support systems, we could even approach cylinder sizes nearing that of the McKendree Cylinders and build several hundred thousand of them. Carbon is the 6th most common element in our solar system and the greater universe. If we develop over the next few hundred years the capacity to use the fullerine allotropes of carbon that align with carbon nanotubes, we could build millions of McKendree cylinders from the available carbon in the asteroid field and jovian moons alone. Space is unimaginably, mindbogglingly big. And the amount of stuff out there, to paraphrase Carl Sagan, makes Earth look like a pale blue dot of dust caught in a sunbeam.

L3 can be useful, if you put something up in L4 and/or L5 to act as relays to Earth.

0:16 and where every colony ever in any gundam show is.

L2 is seriously important for astronomy tho since the light of the sun will always be obscured by the earth and therefore the Lightpolution and heat is minimal compared to any other point in earths orbit.

Lagrange Points are locations where ZZ Top concerts are being held, livestreamed or played back from recording.

I'd love to see more stuff like this. I need to boost my knowledge of space-stuff.

First heard of Lagrange points in Mass Effect. Another great vídeo. 👍👍👍👍👍

I learned about the concept from Freelancer. The Rheinland station "The Ring" was built at the Lagrange point between Planet New Berlin and it's moon.

This is the best video about where to place stations in space based on science fiction ever!

U explained this 3 years back! And now people are searching about L2 because of james webb! U r amazing!!

Ahh, thanks for this, I've often wondered what the importance of Lagrange Points were in many Sci-Fi shows and movies....

This is the best explanation of Lagrange Points I have ever seen - and I've watched dozens of documentaries that discuss the subject.

Sci-fi application ideas: L1: Solar-powered ultra high power installation, such as antimatter factory (for propulsion and weapons) or supercomputational center (for cracking enemy encryption) L2: Defensive mega-telescope with ultracold sensors for spotting heat from ships running dark (think James Webb on steroids). Also gathering point / shipyard for defensive fleet. L3: Other solar-powered installation, possibly shading another mega-telescope to patrol the other half of the sky L4/L5: Loiter point for thermonuclear / relativistic munitions and other first strike-oriented fleet vehicles

Thank you spacedock this has been an ich I've been trying to scratch for months.

Please don't delete this video. Mindblown. Thank you

This makes Gundam much easier to understand and why in terms of where events are happening and where characters are going.

As much as I love sci-fi, the practical science of space travel is equally compelling. Thanks for this!

This video is so great, it does not need visuals. Heck, it could be in podcast form, and anybody could understand it. :)

As a physics student I must say that this is by far the best intuitive explanation of Lagrange Points. I understood them mathematically, but I never got them intuitively, thank you. Also, nice that You mentioned Planetes, it's the best anime.

Thank you Daniel for doing this one, and giving some clarity on it for those that might not understand the basics of an L point. Actual space exploration of course has been using them for many years. Lagrange Points are indeed real, and they're pretty damn cool things. Some may have heard about the SOHO and its mission, but now we're hearing more about Lagrange Points again, as the James Webb is on station keeping at the L2 behind the Earth.

I first heard of Lagrange Points in the pc game Independence War. Thanks for the explanation!

Oh wow. With what I knew from basic orbital mechanics i dismissed those large navy-esque space battles as impossible. But these Lagrange points, they may be actual contested territory between two spacefaring armies.

I first came across the term when I was playing I-War, a great space sim/fighter game albeit bloody hard to play, really needed a multi crew to mange all the systems.

I still find odd that the L-points are ignored in almost every Astronomy class I took. It is an interesting concept because the uniqueness of the orbits on those areas.

Thanks. Really digestible. I’m sure I’ll need more understanding but this is a nice intro to see if one wants to dig more.

"Home, home on Lagrange/ Where the space debris always collects,/ We possess, so it seems, two of Man's greatest dreams/ Solar power and zero-gee sex." -- William Higgins and Barry Gehm

Thank you for this short explanation. I just saw a video about the JWST and in it it mentioned the L2 point. Now I understand more of it. So.. Thanks!

Do more episodes like this, you have the perfect setup for explaining potentially confusing topics found in science fiction.

I must say, I'm loving the new visual style.

Specifically clicked on this video because of the James Webb’s future position at L2. Then you took the time to talk about the observatory specifically!! If that didn’t earn you a subscription, I don’t know what else could.

This was very informative to me and may come in handy in my project. Thank you.

By place a comms satellite at L4 or L5 the further L3 could be easily used !

This is the first time I've ever heard of Lagrange Points and I can't understand why! They are amazing concepts and need to be used way more often in scifi. That would be badass!

There was a series of space sim on PC that used the Lagrange point as jump gates. The series was called I-War (or Independence War in North America). Nice concept!

Does absolutely anyone remember the underrated but excellent PC game "Independence War"? It was marketed only as a testbed for the pre-nVidia 'Voodoo FX' drivers and effects as "the starship simulator" but the lore and gameplay were solid. In that fiction, LaGrange Points are used as de facto jump points for ships' FTL drives (called Capsule Drives in lore) because of the gravitational neutrality. Earth's L1 point is monitored by 'SaltLake STC' which also marks the first time I heard 'Space Traffic Control' used in a sci-fi, now standard in series such as The Expanse and others. Was such a good game, LaGrage points immediately made me remember it!

Daniel, I love your content and your style. I’d listen to you describe anything space-related, sci-fi or not.

1) L1,2,3 points aren't exactly 'stable'. They do require thrusters to maintain the position. It is just that the balanced forces from the two objects means that there is a lot LESS fuel needed.

Learn something new every day!

Fantastic. I knew about the Lagrange points but only nebulously. This clears that up nicely. Thanks!

Ah, why do aliens always have to be a menace to Earth?

Didn't know about 3, 4 and 5. That's really, really cool.

L3 sounds interesting... Thank you so much for the inspiration!

You could easily voice a documentary or educational video on real-life space exploration-related subjects. Well done!

I think this concept is really interesting. I'm currently writing a Sci Fi book and I think the Lagrange points will be a very cool adittion to the plot (specially L3). Thanks for this awesome video. I really love this channel and I wish you the best of luck with your Sci fi series. Live long and prosper!

Gundam UC Era would have been a good one to mention as all of the colony designs used are O'Neil Cylinders of the Island pattern (One and Three), an actual real design for colonies, placed in the Lagrange Points around Earth. All of the technology in that timeline is also explained in realistic terms similar to the Expanse levels of realism. No magic gravity plating or even FTL Gundam of the UC era is a set of series you might want to look into for Spacerdock.

I had heard the term Lagrange point used in sci fi before, but never had a clue what it meant. The name of the L5 Station in Xenosaga makes total sense to me now.

I guess Star Trek would not be considered "more grounded Sci-Fi", however, there is an episode of The Next Generation in which a Lagrange Point was mentioned. In the phenomenal episode, "The Survivors" in the 3rd season, an alien ship that had allegedly destroyed a Federation colony was said by Commander Riker, to have been hiding in a Lagrange Point as the Enterprise had not detected it when it entered the star system in question.

Very good, though I should add that Lagrange points are never fully stable because the gravity of other planets, passing stars, etc, make the system chaotic. A positive side effect of this is that once you’ve reached one L point you can, slowly, transfer to any other L point in the solar system for very little energy.

I love how the diagram showing all five points is a peace sign.

Excellent video! Thorough explanation and interesting.

It was interesting to listen to this. I'm currently making notes for fiction that will be my own version of the old Space:1999 series and I intend to base the moon's travels around Lagrange points being where wormholes can be formed because of the balanced gravity.

Thank you SO MUCH. I've read up on Lagrange Points before and just got lost in the technical jargon and mathematics. A single video, less than 5 minutes long and I feel I know enough to understand the TUL5 Station a hell of a lot better than I did. Thank you again.

I picked up some of this a long ways back from the I-war series of games, a series Spacedock would probably enjoy as a pretty grounded space combat game. In I-war, ships travel faster than light using a device called a capsule drive, which is disrupted by the pressence of gravity fields, so can only be activated within a Lagrange point.

Lagrange points are not where gravity from the two massive bodies cancels out (for example L2 where both forces are in the same direction so can't possibly cancel each other out), but where both gravitational forces cancel out with regard to the centrifugal force that drives the object outwards. Secondly, there is a limitation for the existence of Lagrange L4 and L5 points: the ratio of both masses need be greater than 25.

Thanks for the explainer. I'm a big fan of BattleTech and this explains well how jump points work within the universe fiction.

So two questions, I’m actually serious and both of them: 1. If a sufficiently large enough station was placed at L4 or L5 of any body with that in turn create its own Lagrange points between the station ang the body it was orbiting? Intern with the occupation of these points also create additional points and so on?? 2. Coming in from number one, could/did the death star have had Lagrange points (in legends or canon). Ironically the first time ever heard the word Lagrange point was an outlaw star, not exactly the most grounded sci-fi space anime out there but they never explained what it was.

If I'm not mistaken I have a minor correction for an error in the sentence starting @ 1:13 A satellite placed in L1 will not remain equidistant to the earth and sun but will maintain a constant ratio of distance to earth/ distance to sun.

Ive heard this explained in audiobooks so many times, but never made much sence without the visuals.

Awesome vid! Totally makes sense to me now why the Ancients in Stargate Atlantis built point defense satellites at the lagrange points of their solar system.

Already knew this. Sci-Fi buff. 🤗😀 But different style of vid for you. Good concise, clear explanation. Great vid as usual. Hopefully you continue this sequence.👏👍 When we go interplanetary, or interstellar the moon's L4 and L5 points would be great positions for shipyards. Plus it's L1 for intra lunar communications (equivalent to geo-sync), earth to lunar comms and traffic control/rescue. Lastly via L4 or L5 the L2 could do the same for the farside. Perhaps you could explain orbital monouvers in a similar vein. Aiming/thrusting up to move forward around an orbit (eg docking monouver)) and vice versa. Or thrusting aiming/thrusting backwards to drop to a lower orbit (eg de-orbit burn). And thrusting forward to climb into a higher orbit.😉

In one of my favorite sci-fi book series' Earth-Luna L5 Is home to a large space station, as well as a horde of asteroids used to threaten colonies on Luna, and to attempt an extinction level event on Earth.

Finally! Someone explained this!

Very informative, good work! The humor is definitely an entertaining part too.

This is a great video. Realistically, however, you will always need some thrusters and a Reaction Control System (or some equivalent system(s) that can do the same job) because of all the other bodies in the solar system. The Lagrange points are very stable, but not 100% perfect unless we can somehow make all the other celestial bodies disappear, leaving a true 2-body system. I feel it would’ve helped to reiterate this point towards the end.

This is such an awesome idea for your channel! I absolutely enjoyed this. Please consider doing more of these sort of summaries of scientific terms. Keep up the great work!

My first encounter with the word Lagrange (the ZZ Top song of that same name not withstanding 😉) was when I was in high school and encountered the scifi novel The Mote in Gods Eye by Larry Niven and the late Jerry Pournelle. I seem to recall that the Lagrange Points in the Universe of that book were the ingress points and egress points for FTL travel according to how their FTL tech operated. The FTL tech was called the Alderson Drive as I recall.

Lagrange points 1,2,3 still require control thrusters to maintain their points. The two biggest reasons for that is interaction with other planetary bodies in the system as well as gravity isn't always 'even' from an object which is rotating will cause an oscillation. Hence why there are no permanently stable orbits around our moon, the moon has areas of higher gravity and lower gravity due to uneven density so any craft orbiting it will eventually have an unstable orbit.

Placing structures at L4 and L5 is dangerous, because there are a lot of objects which were captured or will be captured there. That's one reason we send equipment to L1 and L2 - no other objects hanging around there because everything that can't actively stabilize its position will be ejected eventually.

Awesome!!! I heard of Lagrange 1 in Jules Verne book "From the Earth to the moon" and other sources... I never thought about the others Lagrange points, which as you pointed will be very useful for our civilization in the future. A way to have a colony in L3 in communication is to another 2 colony's in L4 and L5. :) Thanks for the video, I Love it!

You still make it sound like science fiction, very cool 😎

I like the idea of the Sojourn. I think it will be a fantastic show! Great job Spacedock!

More of these kind of vids would be great

The Lagrange points were used in the Gundam series, some of the main colonies were named after the Lagrange point they were stationed at. The L3 colony ended becoming the Principality of Zeon.

James Webb!! Cheers and thanks bro. Merry Christmas and happy holidays Daniel!! Wishing bon voyage to JWST!!

What a interesting thing I learned today. Thanking video for making such knowledge ble videos.

Lagrange Points can only exist in 2-body systems where the greater mass is at least 25 times more massive than the lesser mass, and that lesser mass needs to be in a near-circular orbit -- an orbit that isn't too eccentric. Other than that, the info in this video is correct.

This was such an excellent video. As a long time patron I say feel free to do as many real science videos as you please. 💜

Great vid, Daniel. Thanks!

Also in BSG lore with multiple planets sharing the one orbit at the Lagrange points, such as Aerilon and Canceron being located at the Lagrange points of the gas giant Hestia.

A couple questions: 1. How much gravity do LaGrange Points have? Is there a direct relationship to the strength of that points gravity when compared to the celestial bodies that created it? 2. Are LaGrange Points taken into account when trying to predict the orbits of the planets? 3. Do Lagrange Points create gravitational lensing? Efforts are currently underway to use the suns gravity as a telescope, thanks to the gravitational lensing the sun creates. If these LaGrange Points have the necessary gravity, could they be used the same way as, "Gravity Telescopes", so to speak?

A lot of anime sci-fi I see just use Earth-Luna Lagrange points. Same principle applies so good to know.

Excellent. I knew of L2 as it was referenced a long time ago (I was 13?) when I read 2001:A space odyssey, and the resting place of Discovery One between Io and Jupiter, as described in 2010: The Year we Make Contact (Although I thought it was another of Jupiters moons, but that wouldn't make sense). I had no idea there was an L4/L5. That's really interesting.

Excellent! clear and concise!