A sea of mystery. ⁣ ⁣ This spiral galaxy, found 220 million light-years from Earth (and seen here by NASAHubble), is known as a "jellyfish" galaxy because of the blue ribbons of stars that trail from it like cosmic tentacles. When viewed in X-ray light, though, an even longer tail of hot gas emerges which extends across 260,000 light-years of space—shown here in purplish-blue with data from NASAChandraXRay.⁣ ⁣ The newly-forming stars in the tail are a mystery to astronomers. Galaxies that live in a cluster tend to stop forming new stars sooner than galaxies outside of clusters. The “jellyfish” galaxy in the cluster is getting pulled in by the cluster’s gravity which causes the gas to act like wind and can remove the gas and dust in a process called “ram pressure stripping”. ⁣ ⁣ Since galaxies need gas to form stars, this will then slow the process of star formation. Astronomers hope to learn how the stripping process changed over time and how that affected conditions to form new stars....