When the Hooker Telescope first looked skyward in 1917, no one knew what wonders it might reveal. Within a decade, astronomer Edwin Hubble used it — then the largest telescope in the world, at 100 inches across — to discover that galaxies exist beyond the Milky Way, and that the universe is expanding.
History repeated itself starting in 1949, when the 200-inch Hale Telescope took its first photograph of the night sky. In the early 1960s, astronomer Maarten Schmidt used the instrument to analyze unusual, “quasi-stellar radio sources”— quasars for short. These turned out to be supermassive black holes accreting matter in the centers of galaxies, a science-fiction fantasy when the Hale Telescope was built.
By the 1990s, technology advanced far enough to usher in an era of telescopes 8 to 10 meters across (26 to 33 feet), and the same story played out once more. With an essential assist from the 2.4-meter Hubble Space Telescope orbiting above Earth’s image-distorting atmosphere, these instruments could analyze a few dozen distant Type Ia supernovas — the cataclysmic explosions of white dwarf stars. Shockingly, researchers discovered that the expansion of the universe is accelerating. Again, this was only possible with the increased firepower of the latest telescopes.
Now, astronomers stand on the threshold of a new telescope revolution. During the next several years, researchers expect three instruments that are more than twice the size of their closest competitors to start scanning the skies. And a fourth telescope, one “only” 8 meters in diameter, will use advanced technology to image the entire night sky every three days.
This quartet of new instruments promises to deliver stunning science on the hot-button issues. But, as with the previous great leaps forward in size, the new scopes likely will also make discoveries that no one can yet envision. As Pat McCarthy, vice president of the Giant Magellan Telescope (GMT) Organization, puts it: “We expect to learn things we don’t know.”
