Hawaii
* Pros:
* Mauna Kea is one of the best places in the world for stargazing.
* The air is very dry, which reduces the amount of atmospheric distortion.
* The skies are very clear, with an average of 300 clear nights per year.
* Cons:
* The cost of living in Hawaii is very high.
* The site is remote, which can make it difficult to transport equipment and personnel.
* There is some concern about the environmental impact of building a new telescope on Mauna Kea.
Canary Islands
* Pros:
* The Canary Islands are part of Spain, which is a member of the European Union. This means that there is a lot of support for scientific research in the islands.
* The cost of living is lower in the Canary Islands than in Hawaii.
* The islands are much closer to Europe, which makes it easier to transport equipment and personnel.
* Cons:
* The weather in the Canary Islands is not as consistent as in Hawaii.
* There is more light pollution in the Canary Islands than in Hawaii.
In the end, the decision of where to build the next-generation optical telescope will likely come down to a combination of factors, including the scientific merits of each site, the cost of construction and operation, and the environmental impact.
Here is a table summarizing the key differences between the two sites:
| Feature | Hawaii | Canary Islands |
|---|---|---|
| Altitude | 4,205 m (13,796 ft) | 2,390 m (7,841 ft) |
| Seeing conditions | 0.6 arcseconds | 0.8 arcseconds |
| Light pollution | 21.6 mag/arcsec² | 20.8 mag/arcsec² |
| Sky coverage | 300 clear nights/year | 250 clear nights/year |
| Cost of living | Very high | Lower |
| Distance from Europe | 10,000 km (6,200 mi) | 3,000 km (1,860 mi) |
| Environmental impact | Some concern | Less concern |
