Today is the birthday of German Philosopher Immanuel Kant, born April 22, 1724, who was the first person to suggest that nebulae were galaxies or ‘island universes’ at incredible distances. A contemporary of the French Astronomer Charles Messier, Kant made this assertion while Messier was compiling his famous ‘catalog’ of celestial objects that were clearly neither stars nor comets, which is what Messier was searching for. But when the word nebula originally entered English in the early 15th century, it had nothing to do with astronomy. Arriving as nebule meaning a cloud or mist from the Latin word nebula meaning mist, which in turn came from the Proto Indo-European root word *nebh-meaning cloud, vapor, fog, moist, sky. Ancient Greek had the related word nephele, nephos which also meant cloud. When the word nebula reappeared in English it had a medical meaning for cataracts or cloudy defects in the eye. The astronomical meaning of a cloud-like patch in the night sky was first recorded around 1730. It wasn’t until the early 20th century with the advent of modern and powerful telescopes that nebula were fully understood as massive clouds of gas and dust.
Image of the Ring Nebula, courtesy NASA from Hubble Space Telescope Program.