WHAT does the phrase ''first light'' mean to you? For the general population, it might allude to a long night broken by approaching dawn. To astronomers, it signals party time!
It's the birth of a telescope; the first moment an instrument opens its eye to the universe and welcomes the fall of darkness.
This month marks the 95th anniversary of the first night the Hooker 100-inch (or 2.54-metre) telescope, atop Mount Wilson in California, reflected the starry sky in 1917. It was a ground-breaking instrument and remained the largest telescope in the world for decades.
The driving force behind this project, and indeed a number of significant others, was American astronomer George Ellery Hale. He established Mount Wilson Observatory early in the century with its 60-inch telescope - the world's largest until the 100-inch - after reading that philanthropist Andrew Carnegie was making $10 million available to science via the Carnegie Institute, and convinced them to put up the money for the project.
The next step was to go even larger with the financial assistance of John D. Hooker, a successful Los Angeles businessman, and make the 100-inch. It took years for the mirror, telescope and dome to be ready, overcoming disruptions to industry from World War I.
This powerful new astronomical tool provided views of the heavens that allowed us to see that the universe is vast and expanding. Until this time, it was largely thought our Milky Way galaxy comprised the whole universe, and spiral structures in ''nebulae'' seen in smaller telescopes were deemed to be solar systems in the making.
This telescope was able to discern individual stars in the spiral structure of the ''Great Andromeda Nebula'', as it was called then, with Edwin Hubble proving it was another galaxy in its own right. An increase of 40 inches in mirror diameter increased the size of the universe by an infinite amount.