December 18, 2020 A popular theory of galaxy formation suggests that small galaxies merged to form larger ones. But galaxy C1-23152 – 12 billion light-years from Earth – apparently formed itself from gas in the early universe, via exceedingly rapid star formation. C1-23152 rose to a mass of 200 billion suns in just 500 million years. At the height of its star formation, C1-23152 produced roughly 450 stars per year, or more than one per day. The Milky Way, by contrast, produces about two stars per year. Image via INAF/ HST/ NASA/ ESA. An international team of astronomers said on December 10, 2020, that they’ve been able to piece together the growth and rapid evolution of a large galaxy in the early universe. This galaxy, known as C1-23152, existed at a time when the universe was just 1.8 billion years old (in contrast to its current estimated age of about 13.8 billion years). The astronomers acquired 17 hours of observations – coordinated by Paolo Saracco of the Istituto Nazionale di Astrofisica in Italy – using the University of Arizona’s Large Binocular Telescope. These researchers learned that this galaxy formed in only 500 million years, which may sound like a long time, but is a very short time on a cosmic scale to give rise to some 200 billion suns. To do it, the galaxy must have produced as many as 450 stars per year, or more than one star per day.