The universe is a pretty dark place – but according to astrophysicists it is much too dark.
Scientists have been left scratching their heads after noticing there is a huge deficit of ultraviolet light.
The amount of light in the universe can be measured accurately by studying tendrils of hydrogen which become ionised when they encounter ultraviolet light.
The more ionised hydrogen you can spot, the more light should exist.
But, according to a new study in Astrophysical Journal Letters, the hydrogen tendrils suggest there is far too much ultraviolet light than should be being emitted by galaxies and quasars.