In their main sequence, red dwarfs have a lifespan of 100 billion years. Their total lifespan is in the trillions, compared to the 10-billion lifespan of sun-like stars (via Swinburne). They are completely convective, meaning that energy cooked up from a red dwarf core is sent to the surface, where it cools down before returning to the center. This means that no helium builds up in a red dwarf’s core — a requirement for the red giant phase that our sun will go through billions of years in the future. Instead, once the hydrogen runs out, the star collapses on itself and becomes a white dwarf.

Red dwarfs are hard to distinguish from brown dwarfs, which never reach the fusion stage and aren’t considered stars at all. The main way scientists distinguish between the two is by measuring their atmospheres. Finding certain temperatures or chemicals is key in determining their classification. And determining which dim stars are red dwarfs is important as they can be used to locate hospitable planets. Notably, smaller, Earth-size planets can orbit them at close distances and still support organic life. Indeed, the next step in the search for alien life may be in the hands of a red dwarf star.