The James Webb Space Telescope is a marvel of technical engineering. It weighs about as much as a school bus, and it orbits the sun around 932,000 miles (1.5 million kilometers) from earth, gathering light from farther away than any telescope before it. A tennis court-sized sunshield protects it from the sun’s heat and blocks much of the sun’s radiation, enabling it to detect light radiation from enormous distances without interference.

Telescopes can be ranked by effective optical aperture – the diameter of their light-gathering surface. This list includes optical telescopes, but not radio dishes or X-ray telescopes. Here are the seven largest space telescopes, measured by aperture width:

1. James Webb Space Telescope: 256 inches (6.5 meters)
2. Herschel Space Observatory: 138 inches (3.5 meters)
3. Hubble Space Telescope: 94 inches (2.4 meters)
4. Nancy Grace Roman Space Telescope: 94 inches (2.4 meters)
5. Planck: 59 inches (1.5 meters)
6. Euclid: 47 inches (1.2 meters)
7. Kepler: 37 inches (0.95 meters)