Beyond its patriotic appearance, the image offers a rare look at a stellar system that has survived for nearly the entire history of the universe.

A 13-Billion-Year-Old Star Cluster

The featured object is NGC 6426, a globular cluster located in the outer halo of the Milky Way. Globular clusters are dense, spherical swarms of stars that remain bound together by gravity. About 150 of these ancient clusters are known to exist within our galaxy.

Most of the stars in a globular cluster are born from the same collapsing cloud of gas, so they tend to be roughly the same age. NGC 6426 is estimated to be around 13 billion years old, making it one of the oldest globular clusters in the Milky Way. Since the universe itself is about 13.7 billion years old, this cluster formed not long after the cosmos came into existence.

That extraordinary age makes NGC 6426 a valuable record of conditions in the early universe.

What the Colors in the Hubble Image Mean

The vivid colors are not simply for visual appeal. They represent different wavelengths of light collected through Hubble's filters and processed using standard scientific techniques.

Blue highlights shorter wavelengths of visible light, while red represents longer visible wavelengths as well as some near infrared light. Because a star's color is closely linked to its temperature, the blue stars are hotter and the red stars are cooler.

Ancient Stars Reveal the Early Universe

The stars in NGC 6426 have what astronomers call low metallicity, meaning they contain relatively small amounts of elements heavier than hydrogen and helium. This chemical makeup closely resembles the composition of the young universe, when almost all matter consisted of hydrogen and helium and heavier elements were only beginning to form inside massive stars through nuclear fusion.

Scientists have also found evidence that the cluster contains two chemically distinct populations of stars. This discovery suggests that the slightly younger stars formed after an earlier generation of massive stars ended their lives in powerful supernova explosions.

Those explosions scattered newly created heavy elements throughout the cluster, enriching the gas that later gave birth to another generation of stars. The same process gradually filled the universe with the ingredients needed to create planets and many of the elements found throughout the cosmos today.

Hubble Continues Uncovering the Milky Way's History

NASA captured this image as part of an ongoing study of globular clusters in the Milky Way's halo. By measuring their ages and examining their chemical composition, astronomers hope to better understand how our galaxy formed and evolved over billions of years.

For more than 30 years, the Hubble Space Telescope has transformed our view of the universe through groundbreaking discoveries. Today, its observations are complemented by NASA's James Webb Space Telescope, which studies the cosmos in infrared light, while the Nancy Grace Roman Space Telescope, scheduled to launch in late summer, is expected to further expand our understanding of the universe.