The summit of Mauna Kea in Hawai’i is one of the best locations on Earth for astronomical observatories. There are many reasons why it is so. The summit is more than 4000 meters above the mean sea level which means that almost half of the mass of the atmosphere is below the telescopes and does not disturb observations. Mauna Kea is also far away from city lights which helps to make the sky above the summit as black as possible and location in the middle of the Pacific guarantees that there is as small as possible amount of industrial pollutants in the air.
The air above the Mauna Kea summit is usually very dry which means lots of cloudless nights. Tropical temperature inversion is well below the summit (it fluctuates between 1200…2400 meters, if present) which protects it from particulate matter from volcanoes and industrial sources and moisture from the ocean. Temperature inversion means that air temperature increases as we go higher. This is unusual situation. As we know, it usually gets colder as we move higher. If there are inversion layer in the atmosphere, it blocks clouds and pollutants from going up because they are cooler and can not penetrate hotter atmosphere above. It is a common phenomenon in many places and when that happens above industrial cities, it means bad air quality for its inhabitants. In Hawai’i, such conditions are very common and associated with prevailing trade winds that blow from northeasterly direction. The inversion is present about 50…70% of the days. Apparently, the inversion was not present on the day I visited the summit because you can see lots of clouds on the pictures below.
Mauna Kea is home to many telescopes operated by scientists from more than 10 countries. Here are some of these telescopes:
Subaru Telescope (on a cinder cone), Submillimeter Array (small telescopes in the foreground), W. M. Keck Observatory, and NASA Infrared Telescope Facility from left to right. There are no summit crater on Mauna Kea. Its top is covered with conical cinder cones.
One radiotelescope of the Submillimeter Array.
Submillimeter Array telescope from another angle.
W. M. Keck Observatory is the largest telescope in the world. This observatory actually has two domes (picture below), each one hosting a telescope with a 10-meter reflector. This is northeastern dome.
NASA Infrared Telescope Facility, Canada-France-Hawaii Telescope, Gemini Northern Telescope, and University of Hawaii 2.2 m Telescope.
Gemini Northern Telescope and Canada-France-Hawaii Telescope.
Subaru Telescope, W. M. Keck Observatory (both domes visible), and NASA Infrared Telescope Facility.
Caltech Submillimeter Telescope, James Clark Maxwell Telescope, Submillimeter Array, and Subaru Telescope.
W. M. Keck Observatory (northeastern dome).