杏吧原创

THERE are people who like solar eclipses and then there are umbraphiles, those who like them so much they鈥檒l drop everything to see one. On 23 November, a total eclipse is due over Antarctica and dozens of 鈥渟hadow-lovers鈥� will set off 鈥� their mission, as always, to reach the path of totality, where the full shadow of the moon hits the Earth and the sun is completely covered.

What are their prospects? Chasing any total eclipse is a formidable challenge. The path of the moon鈥檚 shadow is only 100 kilometres wide, it often passes over sea or inaccessible areas of land, and a cloud during the crucial few seconds or minutes could ruin everything. In this instance, one group is planning to sail into totality on an ice-breaker, another is going overland to the Russian Antarctic station at Novolazarevskaya, and a third has chartered a Boeing 747.

So what is it about eclipses that鈥檚 exciting? Glenn Schneider of the University of Arizona鈥檚 Steward Observatory, the world鈥檚 leading umbraphile with 23 eclipses under his belt, talks of the majestic sweep of the lunar shadow and the stilling of the wind. Just before totality, points of brightness called Baily鈥檚 beads appear on the edge of the moon as sunlight shines through its valleys. A few seconds later, all that is left is the thin white glow of the sun鈥檚 corona, the solar atmosphere that can only be seen during a total eclipse.

If that鈥檚 not enough, the umbraphile can contemplate this: it鈥檚 a happy accident that the moon is 400 times smaller than the sun and also 400 times closer, so their discs appear exactly the same size in the sky. If they didn鈥檛, eclipses would be much less spectacular.