We finally know exactly how dark deep space is

We finally know just how dark it is in deep space. NASA’s New Horizons spacecraft has made the first precise measurements of the ambient light that suffuses the universe, called the cosmic optical background.

The cosmic optical background is so dim that it is impossible to measure with any precision from Earth – the glow of objects in the inner solar system far outshines it. “Every time you try to measure it from Earth, or from near Earth, you’re…