Dec 13 - Dec 16
San Pedro de Atacama is a place I visited in 2010 specifically to do astronomy. I was looking forward to repeating that experience this year. Unfortunately what I encountered is described in my rant below.
San Pedro is high. Even getting there takes you above 10,000 feet so we were recommended to be on Acetazolamide(Diamox®) I had been on it many times before so one more time was not a problem.
The last time I visited was in Winter so I remember the cold wind blowing at night. Temps this time were cool, but jacket cool unless you were in the wind.
Our arrival day coincided with the Gemini meteor shower. I was really looking forward to this after hearing the hotel had a real observatory that would be presumably staffed with experienced astronomers. Oh well.
What I did manage to do was to find one of the rare unlighted pieces of the property and hung out looking for the Geminids. Unfortunately the Geminids were largely a bust {at least by the time I gave up} which is why I am not a meteor chaser. I also stayed up long enough to view the Southern Milky Way rising.
Carrie and I split our activities on this day. I had assumed I would need to sleep so I only did an afternoon activity north of the hotel.
This was Carrie's morning trip
The salt flats were located west of the main highway. Within it were several lagoons where the flamingos lived
My afternoon trip took me to an area with interesting geology. Rainbow valley is mostly sedimentary rocks; however, dikes of volcanic material intruded cooking the sedimentary rocks near the intrusion, but leaving those further away unaffected.
I traveled north to Rainbow Valley.
Some of the professionals stayed at the hotel Observatory after closing and got some decent pictures. I only had an iPhone which is not known for its astrophotography, but I thought I would give it a shot
Carrie and I again went out of different trips. We had visited the Geysers in 2010 and did not feel the need to go back. So I did the High Plateau Lagoon trip (which was a hike at 14,000 feet) while Carrie visited the Petroglyphs.
This trip involved a rather long bus ride down to Socaire (just off the bottom of the map) and then a climb up to Laguna Lejia and Laguna en Salar de Aguas Calientes.
We were high
The larger lagoon is set in a wonderful panorama of the distant mountains. Argentina is just on the other side of them.
We hiked down the hill to take a closer look. Fortunately it was down hill although I never had any trouble with altitude. When we compared notes back in the bus everyone said their fingers were tingling which is a side effect of Diamox®
The road we traveled to the lagoons passed the Tropic of Capricorn. This marks the sun's furthest location south during the southern hemisphere summer (and where it is for us on Dec 21st).
This is a small section of the road built by the Incas during their time. If you followed this road you would travel to Cusco and then to Machu Picchu
One of my goals while visiting San Pedro was to see the Alma Array. The Atacama Large Millimeter Array is one of the premier telescopes in the world. This is a radio telescope so instead of domes it is a series of 12 and 7 meter diameter antennas that capture microwaves. Scientist use this to view star systems that are forming. It also played a part in the effort to capture a picture of a black hole.
Unfortunately for my goals, the Alma array itself is located up on a higher plateau behind those distant hills. The location is so high that the support buildings are located on the ridge in the distance. You can see them at 2 O'Clock from the guard shed.
While I tested my high altitude acclimation Carrie went to
a local site where you could see petroglyphs.
Note some of these might be shared pictures. If so thanks to the author. I will be happy to give credit
I’ve traveled all over the world, seeking out excellent locations for amateur astronomy. I even have a 10-inch telescope that collapses into a shipping container, which I used in the Outback of Australia and Costa Rica. I’ve visited the latter three times to view the Southern Milky Way (which is visible north of the equator). I’ve also been to Mauna Kea, Exmouth (Western Australia), Kitt Peak as an overnight observer, South Africa (before I had the necessary practical astronomy knowledge to understand what I was observing), and several other places.
When I visited San Pedro de Atacama in 2010, the city was still shrouded in darkness, even in its center. However, in 2025, I observed a remarkable transformation in the city’s lighting conditions. New hotels, such as the one I was staying in, meticulously illuminate every square inch of their property. This has resulted in a striking light dome that now radiates from the city. While the skies remain relatively dark when your view was away from the city, the city’s location directly south of the hotel meant the Southern Milky Way rose through it. Some moron even decided to illuminate the nearby mountain.
If that was not bad enough the skies were noticeably dusty. We could not get a clear answer whether that was just the wind or a product of the lithium mines in the salt flats. The transparency overhead was still pretty good and most of the world would envy the visibility that remains, but the change since 2010 was noticeable.
The next disappointment as far as this trip went was the poor astronomy program that was presented. Back home I help run an Observatory for the California Parks System and I have been doing public outreach for 20 years. I recognize that TCS was likely limited in its options on how to present the astronomy program given that the hotel had the equipment and thought it had people to run it, but this was the only event in the 3 weeks that was flat out a failure. Just to name two problems the guides did not understand dark adaptation and they did not know how to run the tiny telescope they were using. That were only the top two.
Fortunately I brought astronomical binoculars with me. And I was persistent enough to find a dark spot on the property (which unfortunately I lost the second night due to a water leak). I also discovered that the area outside of my room, while not pristine, was probably about as dark as any place else on the property and had a good south view.
So in the end I got some good binocular views of the Clouds. I stayed up long enough one night to view Eta Carina far enough above the lights to appreciate it. So it was not a total loss.