A small rock in the Atlantic

All about the island of La Palma, in the Canaries.

Click for La Palma, Canary Islands Forecast

Thursday, 21 February 2008

Which Planet Are You On?

Martian Rocks

The peak

And the blue sky on that last one that gives the game away. Yes, it's Earth, not Mars. It's actually the Teneguia volcano, on the southern tip of La Palma. The red colouring comes from iron in the rocks. The reason why there's no visible vegetation is that the volcano last erupted in 1971, just 37 years ago.

Some of these little holes in the ground (just big enough to put both hands in) are noticeably warm on a cool day. Children love them - it's when they realise that this really is a volcano.

Actually, there are a few plants beginning to grow, but as you walk up the cone, the main impression is that you're on another planet. It's very hard to believe that you're only about twenty miles from a cloud forest.

The peak

All the Canary Islands are volcanic, but La Palma is still a baby in geological terms, and still growing. The eruption of Teneguia made it half a kilometre longer. Much of the new land is now banana plantations.

Luckily, Canarian volcanoes don't BANG! so much as gently ooze. The eruption of Teneguia only killed one person: an elderly man who was overcome by fumes.

The summit is only about 400 m above sea level. You can walk all the way to the top, but be warned that the path is very rough in places. Stout trainers are about the minimum footware, and walking boots are better.

Lava field

You can start walking from the visitor centre of the San Antonio volcano, or a little lower down on the road from Los Canarios to Las Indias. In fact, you can drive several kilometres along the track, which leaves the road, which only leaves about two kilometres to walk.

And the view from the top is terrific.

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Tuesday, 19 February 2008

The MAGIC telescope

Magic telescope

This is the MAGIC telescope (Major Atmospheric Gamma-ray Imaging Cherenkov Telescope). It's perhaps the most exotic telescope at the observatory at the Roque de los Muchachos.

It's not an optical telescope. Instead of observing visible light, it's looking for gamma rays. Visible light is made up of different wavelengths, which give the different colours from red to violet. Wavelengths which are just a bit too short to see form ultra-violet (the stuff that gives you sunburn). Even shorter lengths are X-rays, and the shortest of all are gamma rays. The snag is that gamma rays don't get through the earth's atmosphere. But as they break up, they create a cascade of particles in the upper atmosphere, and the telescope is looking for these. By looking at the cone of atomic debris, the scientists can work backwards and find out which direction the gamma ray was coming from.

The nearer "basket" won't be operational until next year, but the father "basket" is already going strong. Instead of one big mirror, it has over 1,000 mirrors, each 50cm square, to form a compound mirror 17m (56 ft) across. That's the biggest telescope mirror in the world.

So where do gamma rays come from?

Some come from active galactic nuclei. These are the centres of distant galaxies, which are strangely bright. Astronomers believe this is because there's a super-massive black hole gobbling up the nearby stars. But they don't really understand the details, which is why they're keen to study them.

Supernova remnants are another source of gamma rays. When a large star runs out of its atomic fuel, it creates a massive explosion. Supernova remnants are the smoking gun, and the best available clue to understand supernovas. (Our own star is too small to explode in this way. Eventually it'll just fizzle out, but we have about four billion years before that happens.)

And the final source is gamma ray bursts. These are mysterious bursts of energy, which last anything from twenty seconds to two minutes. There's an orbiting satellite which watches out for them, and alerts the much larger, earth-based telescopes when it sees one. When that happens, MAGIC immediately turns to look at it. It's amazingly nimble for such a huge telescope. The whole basket weighs about 60 tons, but it can slew to point at any part of the sky within twenty seconds.

Arthur C. Clark once said that any sufficiently advanced technology was indistinguishable from magic. So you could say that MAGIC is magic.

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Sunday, 17 February 2008

Los Sauces Sardine Postponed

Los Sauces always hold their Sardine's Funeral a week or two after Santa Cruz. It was supposed to happen on Saturday, but we had an orange weather alert. The rain poured and the wind gusted, and it was obvious that nobody was going out if they could help it. In one way it's a good thing - the reservoirs were very low after such a dry winter.

It's finally stopped raining, so today I phoned a couple of bars in Los Sauces, and politely asked for news. Nope, it's not tonight. It should be on Friday 24th. That sounds good to me.

Meanwhile, you can see some video of last year's funeral here.

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