THE James Webb Space Telescope (JWST) has spotted the smallest galaxy outside our local universe by using the heaviest known cluster of galaxies, called El Gordo, as a giant lens. The mini galaxy is a thousand times less massive than the Milky Way. El Gordo was first discovered in 2011. Follow-up measurements found that it contained so much mass - the equivalent of 3 million billion suns - that it was at the very limit of what standard cosmological theory predicts. This huge mass makes it useful as a gravitational lens, bending and magnifying the light from stars and galaxies on the other side of it that would otherwise be invisible to us.
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