What is Dark Matter? | Space

Roughly 80% of the mass of the universe is made up of material that scientists cannot directly observe. Known as dark matter, this bizarre ingredient does not emit light or energy. So why do scientists think it dominates?

Since at least the 1920s, astronomers have hypothesized that the universe contains more matter than seen by the naked eye. Support for dark matter has grown since then, and although no solid direct evidence of dark matter has been detected, there have been strong possibilities in recent years.