Comet 12P/Pons?“Brooks (bottom) and the Andromeda galaxy (top-right) photographed on 10 March 2024. Pons-Brooks is only visible for a short time every 71.2 years, which is the length of time it takes to orbit the Sun. It was first discovered in 1812 by Louis Pons, and is estimated to be around 30 km in diameter. Comets are collections of dust and ice that orbit the Sun. As they near the Sun and are warmed they release gas (outgassing) that forms the tail.