Magellanic cloud distances

The distance to the Magellanic Clouds was first calculated using the period-luminosity law and measurements of Cepheid variables to be something over 150,000 light years away. This was the first distance estimate to any object outside the Milky Way Galaxy.
 Ejnar Hertzsprung Denmark 1913 Magellanic cloud distances

The distance to the Magellanic Clouds was first calculated using the period-luminosity law and measurements of Cepheid variables to be something over 150,000 light years away. This was the first distance estimate to any object outside the Milky Way Galaxy.