The Einstein ring

The concept

The Einstein ring

Gravitational lenses are often illustrated using images such as the one we use:

This image is informative but misleading. I've often seen turns of phrase, expressions like "light rays on both sides of the Sun"...

But the Sun is not a cartoon drawing. It is a three-dimensional object. In a drawing like this, we depict a two-dimensional cross-section. But in reality, if you were on the focal line looking back at the Sun, in what may be called a "duck's eye's view of a shotgun blast," you'd be seeing light bent towards your eyeballs on all sides of the Sun. Not just two sides. All sides.

That is to say, you'd see the Sun surrounded by a ring of light: the Einstein ring.











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