Animation:

alt="Gif animation explaining weak lensing. When large scale structure appears between distant galaxies and a telescope, lines showing the path of light go from straight to bent. Comic-style speech bubbles show pictures of the galaxies as they would appear for the telescope. When the light is deflected, the images of the background galaxies are distorted." Annoyingly, exporting this as a gif causes the background to become off-white.

Still: alt="Cartoon of weak gravitational lensing. Light from distant source galaxies gets deflected by large-scale structure between those galaxies and a telescope. Comic-style speech bubbles show pictures of the galaxies as they would appear for the telescope, with and without this deflection. When the light is deflected, the images of the background galaxies are distorted."

Unlensed only: alt="Same as above still, but showing only the unlensed case."

Lensed only: alt="Same as above still, but showing only the lensed case."