The phrase “window to the universe” can be read in the marketing blurb of many web sites and Facebook pages connected with tourism and stargazing in the Canaries but where does it come from?
Contrary to the claim often made that it is an accolade granted by NASA, it is actually something much more significant. It is a term used by UNESCO and The International Astronomical Union (IAU) to describe the three very best locations in the world for astronomy and comes from a study commissioned by the IAU in 2010 and again in 2017. The three “windows to the Universe” are the observatories at Hawaii, Chile and both La Palma and Tenerife in the Canary Islands.
Excerpts from the reports:
“There are no better places on the planet from which to observe the skies…”
“The above-mentioned sites are characterised by extraordinarily good sky-quality parameters that determine exceptional windows to the Universe. These are:
- Useful Time (of clear sky).
- Sky background (darkness)
- Atmospheric Extinction (transparency). [The term ‘extinction’ means the loss of light in the atmosphere from a directly transmitted beam. Two different mechanisms contribute to extinction: absorption and scattering.]
- Seeing (for sharp images). [Astronomical ‘seeing’ refers to the blurring and twinkling of astronomical objects such as stars caused by turbulence in the Earth’s atmosphere.]”