Exit Light, Enter Night

Incredibly for the desert, we were awoken last night by rainfall. If San Pedro only receives on average 100mm all year, it must have met this quota overnight.

We awoke to snow covering much of the distant mountains, which until now only had a dusting on their summits. We heard that trips requiring travel over the pass have been cancelled, including those to Uyuni in Bolivia.

Snow!!

Staying in close proximity to San Pedro, we took a walk to Pukará de Quitor - the ruins of a fort - just 3km north of town along the Río San Pedro.

River San Pedro

The fort was constructed in the 12th century by the Atacamenians in order to protect themselves from other bellicose tribes living in South America, most notably their neighbours the Aymara. The ruins still retain the walls of what would have been around 200 living spaces, where the people worked raising livestock, growing corn and collecting fruit from the algorrobo and chañar trees.

A series of small walls

Sadly, this lifestyle came to an abrupt end in the mid-16th century with the conquesting arrival of the Spanish, most notably Pedro de Valdivia, who had a habit of sacking entire villages and beheading the elders. For this reason, the place is also known as "town of the heads".

Heads

Speaking of history, K and I walked the round trip to the top of the hill and back home while drilling the conjugation of the Spanish past preterite tense. We had learned none of this during our two weeks intensive course in Santiago, but conversation quickly becomes dull when we cannot speak about things that have happened in times gone by. In typical Spanish style, there is not one but two 'simple' past tenses (ignoring the composite ones): the preterite, which is used to talk about completed actions and events, and the imperfect, which can be used to relate background context and undefined time periods. For example, "I learned to walk when I was two years old" would be translated as "aprendí (preterite) a caminar cuando tenía (imperfect) dos años". Super.

A quick meal was required after our walk, so I threw together some vaguely 'Chilean' rice. This was basically a pilaf of rice with onion, garlic, tomatoes, chilli, and courgette.

At 8pm, just as the sky had darkened, we were picked up by local Atacameño and amateur astronomer, Jose Corante, for an evening stargazing. He drove us and a small group out into the desert, where he had several telescopes installed in his garden. Sat, snuggled under a warm blanket in the rapidly cooling desert air, we listened as he explained the history and principles of astronomy.

Jose explained the history of the theories surrounding planetary movement and the motion of celestial bodies, from Aristotle and Ptolemy's geocentric movement of the spheres, through the heretical heliocentric model proposed by Copernicus, which demoted God's creation from the centre of the Universe and was not taken at all well by the Catholic church, up to Kepler and Newton's observations of elliptical orbits and proof of the role of gravity in shaping them.

While it is certainly not clear how ancient cultures managed to predict the motion of large bodies, such as the Sun and Moon, for ceremonial and agricultural purposes without such sophisticated equipment as reflecting telescopes to make observations and derive elaborate theories and models akin to those in newly 'enlightened' Europe, there is evidence that they understood and managed to harness the seasons.

Once the Atacamenians settled and began to raise livestock and cultivate crops, they set their agricultural calendar by the position that the Sun rose over the horizon. At winter solstice, the Sun rises directly over Mount Licancabur, while the summer solstice and equinoxes coincide with two other significant peaks visible from the Atacama desert.

While much of this theory might be school-level science for some, Jose presented it in such an entertaining and enthusiastic manner, that we barely noticed the encroaching numbness of our toes. Fortunately a cup of deliciously spiced hot chocolate was presented just at the right moment to defrost us.

Milky Way

With such an expansive view of the southern sky at this latitude, and with little light pollution save for the brightness of the Moon itself, Jose's lecture was set to the unparalleled backdrop of the Milky Way. He equated navigation of the night sky using sky maps to locating a position on Earth using coordinates of latitude and longitude. The difference being that four coordinates - azimuth, elevation, right ascension, and declination - enable astronomers to more easily track bodies as they move, or rather as the Earth turns.

So often, we forget the magnitude of the visible Universe and experience our galaxy and those beyond it as a two-dimensional 'blanket' of stars. Jose's visual explanation - complete with a green laser pointer that seemingly reached into the infinity of space - gave us a three-dimensional frame of reference, in which adjacent stars of equivalent brightness might be four and four hundred light years away, respectively.

Thoroughly conversant with our place in things, we probed the Milky Way courtesy of Jose's telescopes: four 'Dobsonian' telescopes, which simplify the operations to two axes - elevation and azimuth - and two more Newtonian telescopes with control over all four parameters. One of these was motorised, allowing objects to be tracked, as we noticed that, without recalibration, the simple scopes quickly lost sight of the area of the sky on which they had been trained.

Being in the southern hemisphere, the bright North Star is not visible and in the equivalent location in the southern sky, there is nothing remarkable. However, Jose pointed out the southern cross - four stars forming a cross - which was used by navigators, as well as the false cross, which misled them when the southern cross was below the horizon.

Although seemingly familiar with all 88 constellations in the sky, Jose trained the telescopes on the closest stars, as well as distant open star clusters, which burst out of seemingly empty areas of the sky, binary systems, nebulae, planets - the rings of Saturn and the moons of Jupiter were clearly visible - and, of course, the closest body to us: the Moon.

Lunatics

It was an incredible and awe-inspiring evening.