* Astronomy

With lengths over 11m, the giant gypsum crystals found in Mexico's Cueva de los Cristales are a great natural wonder.
Now, a Spanish-Mexican team thinks it can explain how these marvels acquired their immense form.
The scientists studied tiny pockets of fluid trapped in the crystals and conducted back-up lab experiments.
They report in the journal Geology that the solution from which the crystals grew must have been kept in a very narrow, stable temperature range.
The 120m-deep Cueva de las Espadas (Cave of Swords), discovered in 1912, is named for its metre-long shafts of gypsum (a calcium sulphate mineral that incorporates water molecules into its chemical formula).

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