The Seven Sisters are actually thousands of long-lost siblings

Space · Published 26 October 2026 Swipe more like this →

In short: We have long identified the Pleiades as a small cluster of seven bright stars. However, new data reveals that these famous celestial sisters are part of a much larger family. By tracking how stars spin, astronomers have uncovered a massive stellar neighborhood hidden in plain sight.

For centuries, the Pleiades star cluster has been celebrated as the 'Seven Sisters,' a prominent grouping visible to the naked eye and featured in ancient texts like the Old Testament and the Talmud. However, recent research using data from NASA's TESS spacecraft and the European Space Agency's Gaia mission suggests that this familiar cluster is actually about 20 times larger than previously estimated.

The breakthrough came from a team at UNC-Chapel Hill who shifted their focus from visual proximity to rotational physics. By measuring how fast individual stars rotate, researchers can use spin rates as a 'cosmic clock' to determine age. Because young stars spin more rapidly while older ones slow down, scientists can identify familial associations between stars that have drifted apart over eons. This method revealed thousands of hidden members scattered across the sky.

This shift in perspective changes our understanding of stellar evolution and galactic architecture. It suggests that many star clusters we once thought were independent are actually part of massive, extended families with complex structures. Furthermore, by tracing these 'family trees' back to their birth locations, astronomers hope to eventually identify the specific stellar family from which our own sun originated, providing a clearer map of how the Milky Way took shape.

While the universe is vast—containing an estimated one-septillion stars in the observable universe—these hidden relationships provide a more intimate look at local galactic history. This technique allows scientists to see beyond what is visible to the eye, uncovering a hidden architecture where thousands of siblings remain connected by their shared origins.

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