Lagrange Surface Points on Earth?

[Sturn]

I'm hoping someone here can answer this for me, Google and Wiki-land didn't.

L4 and L5 Earth-Moon orbits have been speculated to be perfect places for orbital habitats in both science and scifi due to them being neutral gravity points.

Are these two orbital positions always centered above a certain place on Earth or do they move? If L4 and L5 were fillled with orbital cities, it would make sense that a downport would arise directly below them IF their position relative to Earth's surface didn't rotate.

Traveller includes a "Lagrange Starport" in Australia that makes me think this might have been placed under an L4 or L5 point (perhaps it was just named after the scientist).

If the L4 and L5 points don't move relative to Earth's surface I would love to know where these surface locations are.

[EDIT] Just realized the fallacy of my speculation. The Moon oribts, so the Lagrange points also must orbit.

 

[rust]

The Lagrange Points of the Earth's orbit would most probably not influence
the location of a starport. While these Lagrange Points are gravitationally
stable, they are quite far away, about 150 million kilometers from Earth, so
it would not matter much where in relation to them a starport on the surface
of the Earth would be.

 

[morfydd]

The L-4 and L-5 points are cited most often due to their locations leading and lagging the moon there are 3 other L points in orbit look here for more data and a great overview

http://en.wikipedia.org/wiki/Lagrangian_point

 

[the angle]

The L-4 and L-5 points are each 1/6 of Earth's orbit away, one leading, one trailing. In other words, they're two months away in terms of orbital period. L-1 and L-2 are the closest.

In terms of your question, however -- LG points are stationary by definition. They don't orbit the planet, they orbit the Sun. So there would be no location that's always beneath them, as there is with a geostationary orbit.

Steve

 

[aramis]

The L-4 and L-5 points are each 1/6 of Earth's orbit away, one leading, one trailing. In other words, they're two months away in terms of orbital period. L-1 and L-2 are the closest.

In terms of your question, however -- LG points are stationary by definition. They don't orbit the planet, they orbit the Sun. So there would be no location that's always beneath them, as there is with a geostationary orbit.

Steve

Steve: those are earth's Trojan points. Same physics, tho.

The L-points are a world-moon-point relationship. The T-Points are a Star-World relationship.

 

[the angle]

You're right, I was thinking in terms of the Sun-Earth interface, not Earth-Moon. (Although they're all L points, but the big L4 and L5 are "also called" trojan points.)

The same principle holds true, though. The L points in question are stationary in relation to the Moon, which is not geosynchronous, so the L points aren't, either.

Steve