# What is a Lagrangian point, and how can I get a bird into one?

After looking up what Lagrangian point meant, I'm pretty sure I'm more confused about what it is. It seems to mean that it's some sort of point in between 2 planets or objects in spaces where a third object would maintain an orbit. Then again, I'm no astronomer.

More importantly, how and on which level of Angry Birds: Space can I get a bird into a Lagrangian point? I ask all this because there is a Game Center achievement called Centripetal Force: Shoot a bird into a lagrangian point, which I'm trying to get.

• Tagged with iOS since I don't think the Game Center Achievements apply on other systems, but I can't confirm this. Feel free to remove the tag if they are. Mar 27, 2012 at 12:24
• You want the bird to be stationary with respect to two gravity centers. There should be a point in between the centers where this can occur. Mar 27, 2012 at 13:14

### Update

The latest update of Angry Birds Space fixes a bug and makes this achievement not only possible, but incredibly easy. A bird now only needs to pass through the intersection of two gravity fields to gain the achievement. There are several levels on which this is possible, including the one listed below and in the comments.

### Original post

A Lagrangian point is a point between two large bodies where if you place a small body with negligible influence on the two larger bodies (such as, say, a satellite between the Sun and the Earth), the gravitational force exerted by the two large bodies is equal in magnitude and opposite in direction such that they cancel each other out, thus enabling the small object to stay in equilibrium in that position in space relative to the bigger object.

Now, that's for real life - in Angry Birds Space, gravitation works somewhat differently - unlike in real life where the gravitational field created by masses reaches infinity, gravity wells in Angry Birds Space only covers a certain area - an area that is conveniently marked out for you with a blue circle. As mentioned above, a Lagrangian point is a point between two larger bodies. In game, this translates to looking out for an area where two different gravity wells intersect.

The map which is most convenient to do this is 2-19, where you are given three large green birds to fire at three planets with significant amount overlapping gravity well to work with. Shoot the bird at the top of the building on the first planet, and the bird should slow down enough to hit the overlapping region between the two planets and hopefully stop there.

NB: I'm playing this on the Android version of Angry Birds Space, so there's no achievements, and thus no way to actually test if this actually will give you the achievement, other than that it fits your description

• +1 Great explanation. I'll have to try this out and confirm I can get the achievement to pop here before I accept, but it looks promising. Mar 27, 2012 at 13:46
• Also works great on Pig Bang level 1-10, you can softly shoot a blue bird straight inbetween the overlapping gravational fields.
– user22639
Mar 28, 2012 at 0:57
• Do you need to do something special? I got a bird into that area but I didn't get the achievement. Mar 30, 2012 at 11:32
• @DisgruntledGoat I've yet to get it as well. Searching around, it appears that nobody really has. In the walkthrough's I've seen, they say they didn't actually get the achievement and asked Rovio about it. It may be bugged. Mar 30, 2012 at 11:44
• @DisgruntledGoat Must have been a bug, the latest version has fixed it and it popped pretty much immediately on this level now. Apr 25, 2012 at 18:19