Astronomers at the University of Warwick, in collaboration with Spanish partners, are repurposing astronomical instruments to measure atmospheric greenhouse gases, using starlight instead of sunlight. The initiative leverages a novel algorithm, Astroclimes, developed at Warwick, to analyze how Earth's atmosphere modifies incoming stellar light.
As starlight travels through the Earth's atmo by Sophie Jenkins
London, UK (SPX) Aug 05, 2025
Astronomers at the University of Warwick, in collaboration with Spanish partners, are repurposing astronomical instruments to measure atmospheric greenhouse gases, using starlight instead of sunlight. The initiative leverages a novel algorithm, Astroclimes, developed at Warwick, to analyze how Earth's atmosphere modifies incoming stellar light.
As starlight travels through the Earth's atmosphere, molecules such as CO2, CH4, and H2O imprint distinct absorption features - called telluric lines - onto the light spectrum. While typically removed by astronomers seeking clean stellar data, these lines can instead be used to determine the composition of the atmosphere.
Marcelo Aron Fetzner Keniger, a Warwick Prize PhD student and creator of Astroclimes, explained, "Monitoring the abundance of GHGs is necessary to quantify their impact on global warming and climate change... Astroclimes can hopefully fill the gap with nighttime measurements."
In July, a field campaign at Calar Alto Observatory in Almeria, Spain, tested the combined use of daytime solar readings and nighttime starlight data to monitor greenhouse gases. Daylight data were gathered using a COCCON network FTIR spectrometer, while nighttime spectra were processed with Astroclimes using the CARMENES spectrograph on the observatory's 3.5-meter telescope.
The COCCON instrument provides benchmark-calibrated GHG data that help validate Astroclimes results. A complementary FTIR device at sea level at the University of Almeria broadened the measurement baseline.
Joaquin Alonso Montesinos of UAL noted the collaboration's value to Spain's energy transition efforts. Omaira Garcia-Rodriguez of AEMET emphasized the COCCON-Spain network's role in strengthening national GHG monitoring to support climate adaptation.
Jesus Aceituno, director of Calar Alto Observatory, added, "These greenhouse gas detections made with CARMENES demonstrate that an astronomical observatory can also serve to monitor our planet's climate."
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