Today in the history of astronomy, the first person to propose the Oort Cloud is born.

| Published: October 23, 2026

NASA's illustration here depicts the positioning of Voyager 2 relative to the Oort Cloud in 2018. Voyager 1 was in a similar location in 2013. Despite how close they appear, the scale of the solar system means it'll take about 300 years for the Voyagers to reach the inner edge of the Oort Cloud. Credit: NASA/JPL-Caltech

Born Oct. 23, 1893, in Estonia, Ernest Opik was based at the Astronomical Observatory in Tartu from 1921-1944. It was there in the 1920s that he began to research meteors and comets, their frequencies, and their speeds. In 1932, he proposed a reservoir of long-period comets that formed a large cloud, orbiting the Sun at the farthest reaches of the solar system .…