Final answer:
Visible light and certain types of ultraviolet (UV) light, namely UV-A and UV-B rays, are the two spectral windows through which light easily penetrates the Earth's atmosphere. The largest-aperture telescope for visible light is the Gran Telescopio Canarias, while UV observations are best conducted with space-based telescopes like the Hubble Space Telescope.
Step-by-step explanation:
The two types of light that easily penetrate the Earth's atmosphere are visible light and certain types of ultraviolet (UV) light, specifically UV-A and UV-B rays. Visible light has wavelengths ranging from approximately 400 to 700 nanometers (nm), and it is the region of the electromagnetic spectrum to which human eyes are sensitive. The majority of this light reaches the Earth's surface without being absorbed by atmospheric molecules.
When examining the spectrum of light transmitted through Earth's atmosphere, UV-A and UV-B are also able to reach the surface, although with more attenuation compared to visible light. It is important to note that some electromagnetic waves, like certain infrared and microwave radiation, are absorbed by water vapor, and thus, higher-frequency waves are best observed from space or high altitudes to avoid atmospheric interference.
The largest-aperture telescopes currently in use for observing visible light and UV-A and UV-B rays are both ground-based and space-based observatories. For instance, for visible light, telescopes like the Gran Telescopio Canarias (GTC) with a 10.4-meter aperture are among the largest in the world. Observing UV radiation, on the other hand, requires space-based telescopes like the Hubble Space Telescope since Earth's atmosphere absorbs significant amounts of UV radiation.