Webb image archive
Webb Telescope's Mirror Size and Material
The size of Webb's primary mirror—6.5 meters (21.6 feet) across—was determined by scientists and engineers in order for the telescope to observe distant galaxies at over 13 bi...
- Date
- Dec 13, 2023
- Observatory
- James Webb Space Telescope
- Credit
- NASA / ESA / CSA / STScI
- Archive ID
- 4199
The size of Webb's primary mirror—6.5 meters (21.6 feet) across—was determined by scientists and engineers in order for the telescope to observe distant galaxies at over 13 billion light-years away. The team also decided to make the mirror segments from beryllium, which is both strong and light.
Beryllium is a light metal (atomic symbol: Be) that is very strong for its weight and is good at holding its shape across a range of temperatures. Beryllium is also a good conductor of electricity and heat, and is not magnetic.