Which term describes a star system where one star periodically blocks light from another?

The term that describes a star system where one star periodically blocks light from another is an eclipsing binary. In this type of star system, two stars orbit around a common center of mass, and their orbits are aligned in such a way that one star passes in front of the other from our perspective on Earth. This periodic blocking creates a characteristic dip in brightness that can be observed as the stars eclipse each other.

Eclipsing binaries are significant in astrophysics because they provide crucial information about the stars' properties, such as their sizes, masses, and distances from Earth. These measurements can be determined by analyzing the light curve, which is a graph of the brightness of the system over time, allowing astronomers to gather data that is otherwise difficult to obtain for distant stars.

In contrast, a globular cluster refers to a spherical collection of stars that orbit a galactic core, while a spiral galaxy is a type of galaxy characterized by its spiral shape and structure. A quasar is an extremely luminous and distant active galactic nucleus powered by a supermassive black hole. Each of these terms describes different astronomical objects and phenomena that do not involve the periodic blocking of light between two stars.