At an altitude of 2,400 meters above the cloud layer on Tenerife and La Palma, a team of professionals begins their workday as the rest of the island prepares for sleep. These astronomers and operators from the Instituto de Astrofísica de Canarias (IAC) endure extreme cold, high humidity, and biological rhythm disruptions to facilitate laborious nights of observation under some of the clearest skies on the planet.
Contrary to romanticized depictions in media, the daily reality involves less stargazing and more data analysis. Nieves Castro, an astrophysicist and support astronomer for the Gran Telescopio de Canarias (GTC), describes her nights as filled with simulations, mathematical models, and programming. While she notes that surprises are rare and routines can be monotonous, unexpected findings occasionally challenge theoretical frameworks. For instance, some of the oldest galaxies studied by Castro have been found to be larger than previously thought, forcing researchers to adjust their understanding of the universe.
Despite the routine nature of much of the work, moments of high intensity occur. Julia de León, an IAC researcher and planetary defense lead for the European Space Agency, recalls the 2022 DART mission where a NASA spacecraft deliberately impacted the asteroid Dimorphos. De León monitored the event in real-time from Chile, tracking the evolving dust cloud as the object rotated throughout the night.
The human cost of working against natural biological clocks is significant. José Antonio Madrid, a chronobiology specialist, warns that this "chronodisruption" can have sustained negative effects on cardiovascular health, mental well-being, and memory. Astronomers typically work shifts of four nights twice a month, followed by rest periods to readjust to daytime life. To mitigate these effects, the GTC control room utilizes adaptive lighting to soften the transition toward morning, and shifts are scheduled to end before sunrise.
Personal strategies also play a role in managing fatigue. Castro attempts to catch the last rays of sunset before ascending to the observatory to sustain energy levels, while avoiding sunlight on her way home to prevent reactivation that would hinder sleep. Beyond biological challenges, the physical environment at the summit presents further difficulties, including low oxygen levels and intense cold.
The GTC, also known as GranTeCan, houses a 10.4-meter primary mirror, making it the world's largest optical and infrared telescope. Its sensitivity to humidity is a critical operational constraint; if moisture levels exceed specific thresholds, the dome must be closed immediately to prevent condensation, potentially ending an observation night within minutes. Despite these hardships, the professionals describe their work as deeply vocational. For locals like Castro and De León, working at such a world-leading center in their home islands is a source of pride, offering a unique opportunity to study objects billions of light-years away while being paid to think.
Sources: El País Ciencia.