Gravity might be the weakest of the four forces, but it's also one of the most unusual. Case in point: The same thing that helps hold the Sun together also keeps us tethered to Earth, and it does strange things to the very fabric of spacetime (like making photons bend around things with strong gravitational fields). Ultimately, objects with mass have gravity, and this gravity distorts the spacetime around it. Consequently, astronomers can also look at distant galaxies and use them as gigantic magnifying glasses.

The Hubble/ESA collaboration team have put together this simple, yet eloquent video that demonstrates how this phenomenon (called gravitational lensing) happens—and it's just 30 seconds long.

To provide some additional commentary on what's happening here:

This artist's impression shows how the effect of gravitational lensing by an intervening galaxy magnifies, brightens and distorts the appearance of a remote merging galaxy far behind it. The viewpoint of the observer moves sideways so that that the distant galaxy merger appears first to one side, where it is faint, and then appears right behind the foreground object and is dramatically magnified and its total apparent brightness increases.

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