The F-number of a photographic lens is a measure of its light-gathering ability, and is expressed as its aperture diameter ...

In this new effort, the research team has found, for the first time, two galaxies that align in a way that allows their ...

A compound lens consists of two lenses. Artificial ones are fused together to counteract each other’s light dispersion. In astronomy, a compound lens can form naturally when two galaxies align ...