Near-Infrared Telescopes on Mountaintops:
* Atmospheric Absorption: Earth's atmosphere absorbs a significant amount of infrared radiation, especially at longer wavelengths. This absorption is caused by water vapor and other molecules. Placing telescopes at high altitudes, like mountaintops, reduces the amount of atmosphere above the telescope, allowing more near-infrared light to reach the instruments.
* Clear Skies: Mountaintops typically have drier air and fewer clouds, leading to clearer skies and better viewing conditions for infrared observations.
* Less Thermal Emission: Even the telescope itself can emit infrared radiation, which can interfere with observations. Cooler temperatures at high altitudes help minimize this thermal noise.
Ultraviolet Telescopes in Earth Orbit:
* Atmospheric Absorption: Earth's atmosphere completely blocks most ultraviolet (UV) radiation. This is because molecules in the atmosphere, like ozone, absorb UV photons strongly. To observe UV light, telescopes need to be above the atmosphere.
* Space Environment: Orbiting telescopes also avoid the effects of atmospheric turbulence, which can blur astronomical images. The stable environment of space allows for sharper and more detailed UV observations.
* Access to All UV Wavelengths: Orbiting telescopes can observe all wavelengths of UV light, including those that are completely absorbed by the Earth's atmosphere.
Examples:
* Near-Infrared: The Gemini Observatories (Hawaii and Chile), the Subaru Telescope (Hawaii), and the Very Large Telescope (Chile) are examples of major telescopes that are located on mountaintops to observe in the near-infrared.
* Ultraviolet: The Hubble Space Telescope is a prime example of an orbiting telescope designed to observe the universe in the ultraviolet, visible, and near-infrared wavelengths.
In summary: The location of telescopes is driven by the need to minimize interference from Earth's atmosphere and maximize the amount of light reaching the instruments. Near-infrared telescopes benefit from high-altitude locations, while ultraviolet telescopes require the space environment to observe these wavelengths effectively.
