OT - Where Is the James Webb Telescope and what is a Lagrange point?

Just as long as they don't pull it out of Uranus. Now that's something you don't want on a telescope.

Ray, pretend for a moment that I don't know anything about metallurgy, engineering, or physics, and just tell me what the hell is going on.

I came across this video that explains LaGrange points. Science is cool.

Layman's explanation: Lagrange points are singular points in space where gravitational effects from multiple bodies (Sun, Earth, Moon mostly, but also sometimes Jupiter) are balanced out and the object appears to "not move" relative to the other bodies. It's a mathematical singularity though, so you never get to the perfect Lagrange point-- get close enough though and you basically stay in the same spot. 

Useful for astronomical missions like looking at other stars / galaxies, or even the Sun since because you're in "the same spot" the whole time, you have constant lighting and viewing geometries, simplifying command and control and things like thermal control. The cons are they're all pretty far away from the Earth in relative terms to other spacecraft, hence you need more powerful rockets to get anything of subtantive mass out there. It's also a pretty harsh environment from a radiation exposure perspective, and the distance makes comms with Earth difficult as well. 

We are by definition 1 AU (astronomical unit) away from the sun which is 93,000,000 miles away.  The telescope will be 930,000 miles away or 0.01 AU from Earth, or precisely 1%.  In other words, the JWT will be a 1 percenter.  Or, just mere coincidence?

The L2 point is quasi-stable - meaning it doesn't hold transient objects in the orbit, they pass through and move off.  So JWST has thrusters that will push it back into the L2 point every so often, as the Sun's gravity is always pulling it back in.  This is why it has a finite lifetime, it only has so much fuel.  The lifetime is expect to be ~20 years, up from the estimated ~10 years because of the accuracy of the launch rocket trajectory and the two burns JWST itself did.

This page tells you exactly where it is and what's coming next.  I can't wait for the science this thing will bring us!

I found this online: "Discovered by the Germans in 1904, they named it a Lagrange Point, which of course in German means a whale's vagina." 

"Where Is the James Webb Telescope?" For those of us old enough to remember when this song written by JIMMY Webb and winner of six Grammy Awards in 1968 was a hit, the answer should be “Up, Up and Away”.

The graphic is right for where L2 is. It's in "the opposite direction from the sun" in that if you drew a line from Earth to the sun, it's in the other direction (not farther along in the same direction, which is where L3 is). 

You don't want it at L3, because then the sun is in the way when you try to send data back to Earth.

You don't want to put it out at Neptune, because it's much harder to phone home (farther away), much harder to get there, it has all the disadvantages of orbiting Earth in terms of thermal problems, and it's so far from the sun that your solar cells won't work very well. 

Space may be the final frontier but it's made in a Hollywood basement
And Cobain, can you hear the spheres singing songs off Station to Station?
And Alderaan's not far away, it's Californication

-RHCP

I HAVE QUESTIONS.  SOOO MANY QUESTIONS. I have read a tone on JWST but haven't seen these answered.

1. At L2, does the Earth completely block out the sun? I assume not.  I would think Earth would look small (at least, smaller than the sun), so it is not totally in the Earth's shadow?

2. What about light/heat from the Earth and Moon.  I assume the sunshield reflects their heat too; however, the moon is at a different angle than the sun/earth (which are colinear, given L2), so does the shield have to rotate a bit to block off all light reflected from the Moon?

3. Can Elon's Starship get to L2?  If so, that'll eventually allow us to service the dang thing.  I wouldn't want to go out there and refuel it in person, however, but like change equipment on it.

By the way -- the reason this thing wasn't launched to Neptune is, the weight penalty.  To get an object from Earth to that distance requires a LOT more fuel, and since our rockets have maximum weights they can launch, adding fuel = reducing size of the payload.  The weight of JWST was already rigorously designed -- they actually would have preferred a larger mirror, but just couldn't add the weight -- so trying to move it any further from Earth on launch would have forced an even smaller satellite.