Why are the Galilean moons (4 biggest) of Jupiter locked in a straight line?

I can see Jupiter really good here on the other side of the planet down by the equator at 2am.

And the moons of Jupiter are always in a straight line. Don't they have an orbit of some sort? Why aren't they moving?

They are moving. You are simply seeing the orbits "edge on". Check the positions of the moons on a particular night, and then check again the following night. They will still generally be in a "straight line", but they will have changed their positions with respect to Jupiter, and each other.

Thread title is still misleading.

Agreed. I was even prepared to post about how this whole thread is based upon someone's misinterpretation of grammar.

But then I realized it was originally started months ago and that the misinterpretation was already pointed out.

-saige-