In astronomy, a light curve is a graph that shows the brightness of light from a celestial object or region, over a certain amount of time. The light is usually in a particular frequency interval or band. Light curves can be periodic, that is they repeat in a regular pattern. Examples are eclipsing binaries and cepheid variables. Light curves can also be aperiodic, that is they are irregular with no pattern. Examples include the light curve of a nova, a cataclysmic variable star, a supernova or a microlensing event. The study of the light curve, together with other observations, can give a lot of information about the physical process that produces it or constrain the physical theories about it.