
thumb|255px|An actinometer instrument from the 1800s designed by John Herschel and used to estimate the temperature of the Sun's surface.
thumb|255px|An actinometer instrument from the 1800s designed by John Herschel and used to estimate the temperature of the Sun's surface.
An actinometer is an instrument that can measure the heating power of radiation. Actinometers are used in meteorology to measure solar radiation as pyranometers, pyrheliometers and net radiometers.
Discovered by embedding cosine similarity (sentence-transformers MiniLM, 384-dim).