Pioneering astronomer Vera Rubin discovers dark matter--the mysterious substance that makes up most of the universe--while confronting sexism, and paves the way for future women scientists in this engaging STEM/STEAM picture book biography. From the moment she first looked out her window at the night sky, future astronomer Vera Rubin was star-struck. Her cosmic questions about stars, galaxies, and the universe gave Vera the drive to build her own telescope and earn multiple degrees in astronomy, despite an army of naysayers who thought women shouldn't reach for the stars. But Vera did reach for the stars. Studying spiral galaxies, she searched the skies all through the night, using telescopes in unheated observatories, some of which barred women until Vera insisted they let her in. And her studies revealed something stellar: evidence for the existence of dark matter, the most mysterious substance in the universe. Today, scientists continue to build off of Vera's groundbreaking work as they strive to better understand dark matter. A trailblazing scientist, Vera Rubin changed people's understanding of both the universe and what a woman can do.