The effects of weak gravitational lensing by the Universe's large-scale structure on the observed shapes and positions of galaxies

This video illustrates how light from distant galaxies bends past the galaxies and galaxy clusters of the Universe’s ‘cosmic web’. By the time the light makes its way through the cosmic web and reaches us, the galaxies’ observed shapes and positions have changed. This subtle distortion effect is what scientists call weak gravitational lensing. The effect is highly exaggerated in this video, and studies of weak lensing distortions used to measure how mass is distributed in the Universe typically require measurements of millions of galaxies. Rubin Observatory’s Legacy Survey of Space and Time (LSST) will observe billions of galaxies and enable more precise weak lensing measurements than have been possible before.

Alt Text: An illustrated video demonstrating the weak gravitational lensing effects of the Universe's large scale structure that distort the observed shapes and positions of distant galaxies. The video begins with a single white illustrated galaxy in the center as an elongated oval shape, representing the observation of a distant galaxy. The background is a dark blue with criss-crossing light blue filaments made of tiny dots, resembling wisps of smoke or strings of a cobweb. The camera perspective rotates to the left, conveying a sense of 3D. The web-like background fades, and another smaller illustrated galaxy shape appears to the left, representing the origin of the distant galaxy's light. This distant galaxy wobbles and wiggles toward the final observed galaxy on the right, representing how light from that galaxy traveled through space and ending at that single white galaxy from the beginning of the video. The camera rotates back to the original perspective, and a circular teal version of the observed galaxy appears offset from the oval white version, representing the true shape and position of the galaxy if its light had not been bent by weak gravitational lensing. Finally, a dozen additional white and teal galaxy pairs appear all around the image. The white version of each galaxy is offset slightly and elongated or distorted compared to the teal version.