JWST Discovers Milky Way’s Ancient Twin: Fully Formed Spiral Galaxy Found 1 Billion Years After the Big Bang

JWST Spots a Surprising Milky Way “Twin” Formed Just 1 Billion Years After the Big Bang

Astronomers using the James Webb Space Telescope (JWST) have made a remarkable discovery: a fully developed spiral galaxy that existed when the universe was only about 1 billion years old. This ancient system, named Zhúlóng, is now the most distant spiral galaxy ever observed, and its existence challenges long-standing ideas about how galaxies evolve.

For decades, researchers believed that galaxies like the Milky Way—with their organized spiral arms, thick stellar disks, and dense central bulges—took several billion years to form. Early galaxies were expected to be messy and irregular. But the light from Zhúlóng, which has traveled 12.8 billion years across space to reach us, reveals an unexpectedly mature and well-structured spiral galaxy in the infant universe.

A Cosmic Dragon from the Dawn of Time

The research team named the galaxy Zhúlóng, inspired by a mythological Chinese "Torch Dragon" that was said to control light and time by opening and closing its eyes. According to team leader Mengyuan Xiao from the University of Geneva, this name reflects both the galaxy’s fiery appearance and its significance in illuminating the early cosmos.

“What’s incredible about Zhúlóng is how closely it mirrors our own Milky Way,” Xiao explained. “Its shape, size, and stellar mass all resemble what we see in our galaxy today—something we never expected to find so early in the universe.”

A Surprising Similarity to the Milky Way

Zhúlóng’s stellar disk spans roughly 60,000 light-years, with an estimated mass of 100 billion Suns. For comparison, the Milky Way’s disk stretches about 100,000 light-years across and contains around 46 billion solar masses of stars. Despite being smaller, Zhúlóng is astonishingly well-organized for a galaxy formed so early in cosmic history.

A close-up JWST image shows clear spiral features and a defined structure—unusual traits for such an ancient galaxy.

How JWST Found This Early Spiral Galaxy

Zhúlóng was identified during JWST’s ANORAMIC survey (GO-2514), led by Christina Williams (NOIRLab) and Pascal Oesch (University of Geneva). This program takes advantage of JWST’s “pure parallel” mode, which allows the telescope to collect data from secondary targets while performing its primary observations.

“This method lets JWST cover large portions of the sky,” Williams said. “Massive early galaxies are extremely rare, so wide-area surveys are essential for finding them. Discoveries like Zhúlóng show how valuable parallel observations can be in pushing our models of galaxy formation to their limits.”

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