La Palma is home to one of the three most important astronomical observatories in the world. (The other two are Hawaii and the Atacama desert in Chile.) The observatory sits at the top of the island, at the Roque de los Muchachos. It’s a fascinating place to visit, but it’s not normally open to tourists – they’re too busy doing science. However, the IAC who run the site are organising daily guided tours throughout the summer, many of them to the biggest telescope in the world,Grantecan. You have to sign up in advance and organise your own transport up to the observatory. Details here.
There’s a link to recommendations for visitors. That document starts in Spanish, but the English translation starts half way through. Most of the rules are simple and obvious: all children must be accompanied by an adult, don’t leave litter, don’t set the mountainside on fire with cigarette butts, don’t poke fingers at things inside the telescope, especially if they look expensive and fragile.
You can visit the mountain top and see the buildings from the outside any day of the year. But please note:
* Days only, not nights. The William Herschel Telescope could see a candle on the moon, and the MAGIC telescope is even more sensitive. They really don’t like car headlights. Some years ago there was an incident some years ago where a bus shone its lights right at the Herschel’s dome. Now there’s a barrier across the road which is shut a half an hour after sunset, and raised around dawn.
* The road to the observatory is usually blocked for a few days each winter, by snow or landslides. Use your common sense. If the sign at the bottom of the mountain road says it’s blocked, don’t go up. I once rescued a couple of German tourists who’d spent the night in the car in the drainage ditch, after going past the sign, thinking that the weather couldn’t be all that bad in the Canaries. It can. That night it was thick fog, 60 mph winds, and -5C. Thank God they didn’t try to walk, because they’d have frozen to death for sure.
Since the MAGIC gamma ray telescope doesn’t have a building, you get quite a good view from the outside. You can get fairly close by parking on one of the heliports (the bottom left as you go up the hill). From there, a footpath goes closer, and there’s a display panel that explains how the telescope works.
Children under 12 are not allowed to visit Grantecan for safety reasons. (Please don’t lie, because they’ll ask for an ID and then the kid will have to wait outside with an adult.)