Final answer:
The five biggest optical telescope observatories in the world are located in Spain, Chile, and the USA and have primary mirror diameters ranging from 8.2 to 10.4 meters.
Step-by-step explanation:
The five biggest optical telescope observatories in the world are:
- Gran Telescopio Canarias (GTC) - Located in La Palma, Canary Islands, Spain, GTC has a primary mirror diameter of 10.4 meters.
- Keck Observatory - Located in Mauna Kea, Hawaii, USA, Keck Observatory consists of two telescopes, each with a primary mirror diameter of 10 meters.
- Very Large Telescope (VLT) - Located in the Atacama Desert, Chile, VLT consists of four telescopes, each with a primary mirror diameter of 8.2 meters.
- Subaru Telescope - Located in Mauna Kea, Hawaii, USA, Subaru Telescope has a primary mirror diameter of 8.2 meters.
- Hobby-Eberly Telescope - Located in Fort Davis, Texas, USA, Hobby-Eberly Telescope has a primary mirror diameter of 9.2 meters.
These observatories are used for observing celestial bodies and conducting various types of astronomical research.