The Taurus molecular cloud (TMC-1) is an interstellar molecular cloud in the constellations Taurus and Auriga. This cloud hosts a stellar nursery containing hundreds of newly formed stars. The Taurus molecular cloud is only 140 pc (430 ly) away from Earth, making it possibly the nearest large star formation region. It has been important in star formation studies at all wavelengths of Electromagnetic spectrum.
It is notable for containing many complex molecules, such as cyanopolyynes HCnN for n = 3,5,7,9, and cumulene carbenes H2Cn for n = 3–6. In 2007 the polyatomic anion octatetraynyl radical was detected in TMC-1, making it the second type of anion to be found in the interstellar medium and the largest such molecule detected to date.