The sun warms our planet, and the Earth releases a huge spectrum of radiation in the universe. Light is only a small part of this spectrum, namely, the visible portion of the spectrum – colours of the rainbow. We do not perceive other forms of radiation such as radio waves or microwaves. Light rays can travel through vacuum in the universe, but when they fall on the matter, they get refracted. This phenomenon of refraction is used in instruments such as lenses or glasses for people with weak eyesights.