The Shiva hypothesis, also known as coherent catastrophism, is the idea that global natural catastrophes on Earth, such as extinction events, happen at regular intervals because of the periodic motion of the Sun in relation to the Milky Way galaxy.
William Napier and Victor Clube in their 1979 Nature article, ”A Theory of Terrestrial Catastrophism”,[1] proposed the idea that gravitational disturbances caused by the Solar System crossing the plane of the Milky Way galaxy are enough to disturb comets in the Oort cloud surrounding the Solar System.
This sends comets in towards the inner Solar System, which raises the chance of an impact.
[2] In the 1990s, Rampino and Bruce Haggerty renamed Napier and Clube's Theory of Terrestrial Catastrophism after Shiva, the Hindu god of destruction.
[5] However, a reanalysis of the effects of the Sun's transit through the spiral structure based on CO data has failed to find a correlation.