NASA’s James Webb Space Telescope (JWST) has helped astronomers find a galaxy that seems to be the old twin sister of the Milky Way. With a central bulge of old stars, a vivid disc of stellar babies, and two separate spiral arms, the recently discovered galaxy Zhúlóng is the most distant Milky Way “twin” yet seen. The discovery questions our best models of cosmology, which hold that big galaxies such as this should develop over a difficult succession of smaller galaxy mergers several billion years ago.

Comprising around 100 billion solar masses, larger than the Milky Way, the star-forming disc of the galaxy stretches over 60,000 light-years. Found in 2023, Zhúlóng is by far the largest Milky Way lookalike found in an early epoch of the universe, forming more than a billion years earlier than the similarly organised spiral galaxy Ceers-2112.

JWST Discovers Ancient Milky Way Twin Galaxy Zhúlóng from the Early Universe

As per a study published in the journal Astronomy & Astrophysics, swirling limbs heading back to us show the Milky Way’s former twin. About one-fourth of the present universe’s age, the newly found galaxy called Zhúlóng formed one billion years after the Big Bang. The find tests our top cosmology models, which say that the lengthy process of smaller galaxy mergers over many billions of years makes massive galaxies like this.

Zhúlóng is the largest early look-alike of the Milky Way by far, having grown more than a billion years before Cers-2112, and a spiral galaxy of similar mass and structure.JWST spotted it in 2023 at around 11.7 billion light-years from Earth. No family tree studies were necessary; this long-lost relative was revealed by PANORAMIC, a wide-field look at billions of distant objects, entirely by accident.

The new finding adds fuel to an active cosmic fire started by JWST a few years ago that regularly reveals objects in the early universe looking too enormous and too quickly to fit in with our current best theories. The finding shows how JWST is essentially changing the way we see the early universe, and the researchers are urging follow-up work with JWST and the ground-based Atacama Large Millimetre/submillimetre Array in Chile’s desert to better understand our galaxy’s long-lost twin.