A brown dwarf is another name for a very low-mass star, or a “failed star.” The existence of brown dwarfs—objects that formed like stars with so little mass that there is almost no nuclear fusion in them, yet with much more mass than any planet in our solar system—was not confirmed until the 1990s. The reason is that their photospheres are so cool that they are very dim, emit very little visible light, and can be found only using infrared telescope technology. Since their discovery, infrared telescopes and infrared astronomical cameras have advanced by leaps and bounds. One 110 result is that a huge number of brown dwarfs have been discovered in recent years.

In fact, so many have been identified that it is now hypothesized that the number of brown dwarfs may rival all the other stars in our galaxy put together.