Q. Stars which appear single to the naked eye but are double stars when observed by a telescope, are known as ________ 

Explanation by: Mr. Dubey

Binary stars (or double stars) are star systems where two stars orbit around a common center of mass. They appear as a single point of light to the naked eye but can be resolved into two separate stars with a telescope.

(A) Cosmic stars → Not a specific astronomical term.

(B) Quasars → Extremely bright and distant objects powered by supermassive black holes.

(D) Novae and Supernovae → These are explosive events in a star's life cycle, not double stars.