Mineral Luminescence Observed From Space.

Methods developed to explore the luminescent properties of the moon facilitated the development of techniques to infer terrestrial solar‐induced chlorophyll fluorescence (SIF) from satellite instruments. While single SIF retrievals are inherently noisy, averaging many retrievals allows us to obtain highly accurate estimates. We analyzed several years of aggregated SIF data collected by the TROPOspheric Monitoring Instrument (TROPOMI) and the Orbiting Carbon Observatory‐2 (OCO‐2) over nonvegetated areas to explore the potential of SIF retrievals beyond the realm of photosynthesis. The fundamentally different retrievals at varying wavelengths in the near‐infrared reveal that about 10% of all barren surfaces are weakly luminescent, while a few areas luminesce strongly—amounts comparable to SIF from vegetation. By means of lithological maps, we attributed the strongest luminescence signals to exposed carbonate sedimentary rocks. Besides a detailed evaluation of the signal properties, we discussed implications for SIF data sets and other remote sensing products. Plain Language Summary: During the last decade, advancements in remote sensing techniques allowed us to infer solar‐induced chlorophyll fluorescence, a faint electromagnetic signal emitted by vegetation, from space‐borne measurements. Here, we explored the potential of such measurements to also observe mineral luminescence, a signal that is typically even weaker than fluorescence from vegetation, which explains why it has not been documented to be detectable from space. We identified luminescent regions by means of several years of vegetation fluorescence data derived from two satellites (OCO‐2 and Sentinel‐5P) over nonvegetated areas and analyzed the composition of luminescent surfaces. According to our analysis, about 10% of all barren areas on Earth are weakly luminescent, whereas some areas display surprisingly strong signals. Key Points: First report of mineral luminescence observed from spaceStrongest signals originate from carbonate sedimentary rocksEmission appears to be spectrally flat in the near‐infrared and Lambertian [ABSTRACT FROM AUTHOR]