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Galaxy's Invisible Arms Revealed - Universe Today
Astronomers have discovered that a relatively nearby galaxy is undergoing a tremendous amount of new star formation. This is very unusual, since galaxies normally only went through this phase billions of years ago, when the Universe was much younger. Seen in visible light, NGC 4625 only showed a diffuse halo, with a hint of spiral arms. But in the ultraviolet gaze of NASA's Galaxy Evolution Explorer, it clearly has vast spiral arms which extend four times the size of the galaxy's core.