The Pleiades star cluster is 20 times larger than it looks at first sight, astronomers have learned. The cluster celebrated in cultures around the world, often under the name the "Seven Sisters", is the remnant of something much greater, with hundreds of the original stars having escaped each other’s gravitational grip. The rest of this article is behind a paywall. Please sign in or subscribe to access the full content.

Stars are usually formed together in giant clouds of gas, a process we can see taking place today in stellar nurseries like the Orion Nebula. Initially, gravity holds the young stars together, but as time goes on some acquire enough speed to leave the nest . As each star goes, the gravitational force binding those left behind weakens, and the bar to leaving drops, like e

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