a large group of stars in the sky

Nighttime Sky View of Future Galaxy Merger: 3.85-3.9 Billion Years Caption During the first close approach, the sky is ablaze with new star formation, which is evident in a plethora of emission nebulae and open young star clusters. Credits Science Illustration: NASA, ESA, Z. Levay and R. van der Marel (STScI), T. Hallas, and A. Mellinger