Eclipsing binaries are those systems, seen as a single star, which show periodic changes in brightness. This occurs when one component eclipses the other during their orbital motions around the center of mass of the system. The plane of the orbital motion must necessarily be close to perpendicular to our line of sight; eclipses are further facilitated when their separation is small. By analyzing the brightness with the passage of time, the resulting light curve can indicate some geometric and dynamical components of orbital motion. Astrophysical properties can be determined such as the relative brightness of the two components, their relative diameters, and some aspects of their atmospheres.
Science EncyclopediaScience & Philosophy: Bilateral symmetry to Boolean algebraBinary Star - Importance, Visual Binaries, Study Of Orbital Motion, Astrometric Binaries, Spectroscopic Binaries, Eclipsing Binaries - Techniques of observation