Kant (1724–1804), known today for his philosophy, made some important discoveries about the nature of the Earth's rotation. He showed the frictional resistance against tidal currents on the Earth's surface must cause a very gradual slowing of the earth's rotation. The days have grown longer as time has passed. Also, he laid out a nebular hypothesis, in which he deduced that the Solar System formed from a large cloud of gas, a nebula. Following Wright, Kant also thought the Milky Way was a large disk of stars formed from a (much larger) spinning cloud of gas.