how big is the biggest telescope
The next generation of ground-based telescopes are coming to give us an unprecedented view into the cosmos. Today, the Giant Magellan Telescope was approved to begin construction in Chile. When it opens its eyes in 2021, it will be the largest telescope in the world ... for a little while, anyway. The building of the GMT marks the beginning of the era of extremely large telescopesâthose whose light-gathering surfaces measure in excess of 80 feet. The Giant Magellan will measure just over 80 feet.