A Dramatic Einstein Ring Seen by Webb

One of the first verified predictions of general relativity is the gravitational deflection of starlight. The effect was [first observed in 1919 during a total solar eclipse.](https://briankoberlein.com/post/einstein-and-eddington/) Since stars appear as points of light, the effect is seen as an apparent shift in the position of stars near the eclipse. But the effect happens more generally. If a distant galaxy is obscured by a closer one, some of the distant light is gravitationally lensed around the closer galaxy, giving us a warped and distorted view of the faraway stars. This effect can also magnify the distant galaxy, making its light appear brighter, and we have used this effect to observe some of the most distant stars in the Universe.

Mar 31, 2025 - 19:33

One of the first verified predictions of general relativity is the gravitational deflection of starlight. The effect was [first observed in 1919 during a total solar eclipse.](https://briankoberlein.com/post/einstein-and-eddington/) Since stars appear as points of light, the effect is seen as an apparent shift in the position of stars near the eclipse. But the effect happens more generally. If a distant galaxy is obscured by a closer one, some of the distant light is gravitationally lensed around the closer galaxy, giving us a warped and distorted view of the faraway stars. This effect can also magnify the distant galaxy, making its light appear brighter, and we have used this effect to observe some of the most distant stars in the Universe.