Einstein Cross/Ring

1. Sep 20, 2008

Unredeemed

Why do we ever get Einstein crosses? I realise it is because the alignment is not right, but why do we get a cross because of this instead of just a skewed ring?

Thanks,
Jamie

2. Sep 20, 2008

George Jones

Staff Emeritus
Hartle's book Gravity: An Introduction to Einstein's General Relativity has a nice treatment of this. I can look it up on Monday.

3. Sep 21, 2008

Unredeemed

That would be great, thank you.