A nova explosion of the binary star system T Coronae Borealis, first potentially recorded in 1217, is expected to occur soon. This rare event, caused by a thermonuclear reaction on a white dwarf star, happens approximately every 80 years. Historical observations in 1866 and 1946, along with a recent pre-eruption dip, suggest the next eruption could happen between now and September 2024.
A medieval manuscript from 1217 may contain the earliest recorded observation of a recurrent nova, specifically the star T CrB in the constellation Corona Borealis. The manuscript describes a "wonderful sign" of a faint star brightening and emitting a tall beam of light for several days. The researcher, Dr. Bradley Schaefer, rules out other possibilities such as a supernova or comet and concludes that the observation is likely a misidentification of T CrB during an eruption. If the star follows its previous pattern, it is predicted to brighten again in early spring 2024.