The term 'Brilliant Star' can be broken down into two crossword solutions: DENEB (5 letters) and NOVA (4 letters). DENEB is a star in the constellation Cygnus, which is one of the brightest stars in the night sky. It is also the 19th brightest star in the sky and is part of the Northern Cross asterism. NOVA is a type of star that experiences a sudden increase in brightness due to an explosion on its surface. It is believed that novae occur when a white dwarf star accretes matter from a companion star, resulting in a thermonuclear explosion on the surface of the white dwarf.