How does cosmic background radiation affect earth?
The Cosmic Microwave Background (CMB) is so low in energy that it really has no effect on Earth.
The CMB is the "echo of the Big Bang" - the light produced during the very earliest stages of the universe when it was a hot, glowing fog. Over the last 13.8 billion years, the universe has been expanding, and as it has done so, the wavelength of light passing through that space also expanded, redshifting (stretching) once visible light so that it is long wave, low energy radiation.
It is now roughly equivalent to the heat radiated from an object cooled to 3 degrees Kelvin (
The CMB is of such low energy, that it's affect on Earth is non-existent.