A type of variable star that explodes therefore dramatically increasing its brightness. A nova can appear many thousands of times more brilliant than previously and continue to shine brightly for many days or weeks afterwards. The cause is a cataclysmic nuclear explosion occurring on a white dwarf.
Bright novae in the past include:-
GK Persei (1901: peak apparent mag. +0.2)
V603 Aquilae (1918: mag. -0.5)
RR Pictoris (1925: mag. +1.2)
DQ Herculis (1934: mag. +1.4)
CP Puppis (1942: mag. +0.3)
V1500 Cygni (1975: mag. +1.7)