Question

What are the largest optical telescopes in use today? Why do astronomers want their telescopes to be as large as possible?

Answer 1

The largest telescope currently used is the Gran Telescopio Canarias, (also known as GTC or GRANTECAN). It is 10.4m in diameter, slightly larger than the Keck telescopes in Hawaii.

The telescope observes the visible and infrared light coming from space and has a primary mirror of 10.4 meters, segmented into 36 hexagonal glass-ceramic pieces, 1.9 m between vertices, 8 cm thick, and 470 kg of mass each. The optical system is completed with two mirrors (secondary and tertiary) that form an image in seven focal stations.

Optically the diameter directly influences the magnification of the image. This added to the fact that astronomical objects are quite far away, a telescope of this magnitude allows to obtain more precise images of what is observed in space