W F Denning discovered Nova Cygnus 1920 on August 20th 1920 while observing from his home in Bristol, England. At its brightest the Nova reached magnitude 1.8 which is slightly brighter than the North Star.
Astronomers today believe it was one of the brightest and fastest galactic nova observed. It increased in brightness nearly 13.5 magnitudes and declined 3 magnitudes in only 16 days.
A nova the word means ‘new’ in Latin is a binary star system where two stars orbit close to each other. One star which is hotter than the other will pull gas from its companion onto itself. When enough gas hits the hotter star it sizzles or sends out a shell of gas which makes the star become brighter, we see this and call it a Nova. A Nova can repeat this process several times.
It is believed that the star now called V476 Cygnus is about 4,000 light years away and at its brightest was about 250,000 times brighter than the Sun.