From Kielder Observatory, I can see Mars, Venus and Mercury, and all with the naked eye. I can’t see the rings of Saturn — but only because somebody has stolen them. The planets dangle in a line beside the forest track to the pearl strands observatory, suspended from wooden gallows and wobbling slightly in the wind.

Anywhere else, a row of giant extraterrestrial gobstoppers would be a pretty surreal ornament on top of a remote fell. But Kielder isn’t anywhere else. It’s a whole world of strangeness, and after a couple of days here, the feeling that I’ve wandered into some kind of bizarre sci-fi universe is becoming ever more gripping. Take the observatory itself, which juts out from the heather behind me. Opened last year to architectural acclaim, it comprises several stripped-pine cubes and looks as if it arrived flatpacked from Ikea.

Half a mile along the track, I come upon another surprising structure, hollowed into the side of a crag. Through a tunnel I go, and into an underground dungeon, cone-shaped and weirdly windowless, with a hole at the apex through which the heavens seem to bulge, a  wholesale pearl earrings ball of blue.

This is Skyspace, an installation by the Californian artist James Turrell, and when I stand in the dead centre, my head becomes an echo chamber, and freshwater pearl necklace every sniff or splutter booms like a thunderclap between my ears.
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