NASA’s James Webb Telescope discovers ‘Firefly Sparkle’ galaxy, leaves scientists feeling ‘Christmassy’ in the holiday season

NASA’s James Webb Space Telescope (JWST) has captured its first image of what our galaxy likely looked like in its early formation stages, and the discovery has scientists feeling festive. 

Professor Catherine Heymans, Scotland’s Astronomer Royal, shared her excitement with BBC News: “I just love the sparkle galaxy with its Christmas lights shining as it was when the Universe was just 600 million years old.” 

The image reveals 10 distinct clusters of stars, glowing in different colours like Christmas tree ornaments suspended in space. This marks the first time scientists have observed the formation of star clumps that could eventually evolve into a galaxy similar to our Milky Way, offering important insights into the universe's origins. 

For the first time, JWST has “weighed” a galaxy that not only formed about 600 million years after the Big Bang, but also has a mass comparable to that of our Milky Way during a similar phase of its development. While other galaxies from this era are much larger, this one — nicknamed the Firefly Sparkle galaxy — shines with star clusters, 10 in total, which researchers have studied closely. 

Lamiya Mowla, a co-lead author and assistant professor at Wellesley College, expressed her amazement: "I didn’t think it would be possible to resolve a galaxy from so early in the universe into so many distinct components, let alone find that its mass is similar to our own galaxy’s at the same stage." Mowla, who first spotted the galaxy, was drawn to its shimmering star clusters, explaining that objects which sparkle tend to be dense and complex. This galaxy's appearance — resembling fireflies on a summer night — led to its festive nickname. 

JWST’s data indicates that the Firefly Sparkle galaxy is relatively small, classified as a low-mass galaxy. It will take billions of years for it to gain mass and develop a more defined shape. “Most galaxies we see with Webb are not magnified or stretched, and we cannot view their individual building blocks. But with Firefly Sparkle, we’re witnessing the galaxy forming piece by piece,” said Mowla. 

The galaxy’s elongated shape allowed researchers to easily identify 10 distinct star clusters, each emitting significant light in shades of pink, purple, and blue. Webb’s spectra confirm that star formation in this galaxy did not occur all at once but instead unfolded in phases. 

Chris Willott, from the National Research Council of Canada’s Herzberg Astronomy and Astrophysics Research Centre, and co-author of the study, added, “It’s remarkable that we can observe the separate star clusters at such an early stage. Each clump is undergoing a different phase of star formation or evolution.” 

The Firefly Sparkle galaxy’s stars have not yet settled into a defined shape, such as a central bulge or flattened disk, indicating that the galaxy is still in the process of formation. From its orbit beyond Earth's atmosphere, JWST has captured more distant, older galaxies, but none in such detail or in the early stages of formation like this one. 

“The data from this stage of the universe is extremely rare,” Mowla noted. “This is the first time we are seeing a galaxy as it forms, brick by brick, whereas the galaxies we usually observe are already fully formed.” 

Professor Heymans, who is not part of the research team, called the discovery “gorgeous, scientifically important, and extremely festive.” Heymans marvelled at how humanity has built a telescope capable of peering so far into the past and capturing these early moments of galaxy formation with such a “beautifully festive” glow. 

Mowla, who discovered the galaxy, was initially struck by the bright and varied colours of the star clusters. When she confirmed the galaxy’s distance — over 13 billion light-years away — she was astonished. The light from the Firefly Sparkle galaxy has travelled for over 13 billion years, meaning we are seeing it as it appeared shortly after the birth of the universe. 

Because of a rare cosmic alignment, James Webb Space Telescope was able to observe this small and distant galaxy. Though its future development is unclear, the team has found two nearby galaxies, just 6,500 and 42,000 light-years away, that may influence the Firefly Sparkle galaxy’s mass-building process over time. 

For context, the fully-formed Milky Way spans about 100,000 light-years across, and all three galaxies in this system could fit comfortably inside it. These companion galaxies are close to one another and may even be orbiting together.