The star of the stargazing show, the purpose-built Observatorio Cerro Mamalluca, 9km northeast of Vicuña, is Elqui Valley's biggest attraction. So big, in fact, that you're likely to share the tour with hordes of other tourists, all looking for their chance to goggle at distant galaxies, star clusters and nebulae through a 30cm telescope.
Bilingual guided two-hour tours take place nightly every hour between 8:30pm and 2:30am in summer and between 6:30pm and 11:30pm in winter.
Make reservations through the Mamalluca office in Vicuña; advance booking is recommended. There is no public transportation, but a minivan takes visitors from the Vicuña office (reserve in advance, per person CH$3000). Some La Serena tour agencies arrange trips, or you can hire a taxi in Vicuña.