The Drake equation for alien intelligence is more important than ever
In 1961, the US astrophysicist Frank Drake, who passed away on Sept. 2 at the age of 92, came up with an equation to estimate the number of intelligent civilizations in the Milky Way right now.
![The Drake equation for alien intelligence is more important than ever](http://cdn.mos.cms.futurecdn.net/dxJz3eA23bDoSgLvt7yTx9.jpeg?#)