Almost everything we know about the cosmos today, we have learned by observing different forms of light – not only through the light to which our eyes are sensitive, but also through infrared, ultraviolet, radio, X-ray and gamma ray radiation, which differ from visible light only through their wavelengths.



However, this electromagnetic radiation is only one of four different messengers from the universe, along with neutrinos, electrically charged subatomic particles (dubbed “cosmic rays”) and gravitational waves.