Can you see the dwarf galaxies in the above image, shot by the Hubble Space Telescope? Yeah, me neither. But they’re there, and some of them are working exceptionally hard to make new stars. I’ve included a cheat sheet below so you’ll know which of the galaxies in the image are some of the ones scientists looked at during a recent survey of star formation in the early universe.

Many of the stars we see in the universe today were formed between two and six billion years after the Big Bang. But until now, astronomers didn’t really know how many of those stars were born in dwarf galaxies — the small, low-mass clusters of several billion stars that are too big