Fifty-six years ago legendary astronomer Edwin Hubble ascended to the Hale Telescope’s prime focus cage and began a new era in astronomy. On January 26, 1949 he took the first official photos with the then new 200-inch telescope. In a nod to his own astronomical past, he photographed an object that now bears his name Hubble’s Variable Nebula.
Hubble had first studied this object at the Yerkes Observatory, where he determined that this cloud of gas appears to change its shape. In 1919 he photographed the nebula on his first night of observing at Mt. Wilson’s 100-inch Hooker Telescope. Hubble went on to use the 100-inch to discover that galaxies were large, distant conglomerations of stars and gas, separate from our own Milky Way galaxy, and that the universe itself was expanding.
Edwin Hubble's 1949 photograph from the Hale Telescope of Hubble's Variable Nebula.
Palomar’s Hale Telescope was large enough that Hubble could ride inside the telescope in what is known as the prime focus cage. From that lofty vantage point he and the astronomers who followed him took photographs on glass plates. During the long exposures astronomers had to carefully control the motion of the telescope to ensure that it didn’t wander even slightly off target. It was vital for them to give their full attention to this for many hours. The long dark and cold of Palomar nights required them to be made of stern stuff.
By comparison, the modern astronomers at Palomar have it easy. Observing at the 200-inch takes place in a heated room where they have ready access to computers, a stereo, hot coffee, and even a bathroom! Improvements in techology have made photographic plates obsolete. All modern astronomical imaging is done with digital cameras that are 50 times more sensitive to light than the chemical processes of photography with film.
New technologies allow the astronomers who use Palomar’s 60-inch and 48-inch Samuel Oschin telescopes to completely skip coming to Palomar. The telescopes are now fully robotic. This allows astronomers to get a full night’s sleep while the telescope automatically collects their data; and can also rapidly switch to a newly discovered source of interest. The information is beamed off the mountain via microwave to Caltech and other institutions. The technique has worked well, allowing astronomers to use these telescopes to study gamma-ray bursts and to do some prospecting as they hunt for near-earth asteroids, objects in the outer solar system, and quasars on the farthest shores of the universe.