The Gran Telescopio Canarias (GTC) obtains the visible spectrum of interstellar comet C/2019 Q4 (Borisov). The spectrum acquired by GTC reveals that this object has a surface composition not unlike that found in Solar System comets. https://t.co/crU6zcKFeB #astronomy #comets pic.twitter.com/HvMOLh6w23

— Ernesto Guido (@comets77) September 14, 2019