Rogier A. Windhorst

Thanks to gravitational lens — an effect predicted by Fritz Zwicky, where a galaxy cluster acts like a magnifying glass — the James Webb Space Telescope spotted two red dots in a galaxy 800 million years after the Big Bang.

Light from a distant galaxy travels toward us for billions of years, but along the way it can run into a massive galaxy cluster. Its gravity acts like curved glass: it bends the path of rays, so instead of one image, we see several — sometimes arcs, sometimes points.

Light from the distant Dragon Galaxy has been traveling toward us for more than seven billion years. On its way, it passes by a huge galaxy cluster whose gravity bends the path of light like a lens. As a result, the galaxy appears brighter and larger than it really is, just as a magnifying glass enlarges fine print.

The early Universe is often imagined as a nursery: most galaxies there are amorphous blobs, rowdy and irregular, choking on gas and bursts of star formation.