CC BY 3.0 UnportedKuhn, Jeff R.Berdyugina, Svetlana V.2018-04-162019-06-282015https://doi.org/10.34657/1518https://oa.tib.eu/renate/handle/123456789/4315Earth-like civilizations generate heat from the energy that they utilize. The thermal radiation from this heat can be a thermodynamic marker for civilizations. Here we model such planetary radiation on Earth-like planets and propose a strategy for detecting such an alien unintentional thermodynamic electromagnetic biomarker. We show that astronomical infrared (IR) civilization biomarkers may be detected within an interestingly large cosmic volume using a 70 m-class or larger telescope. In particular, the Colossus telescope with achievable coronagraphic and adaptive optics performance may reveal Earth-like civilizations from visible and IR photometry timeseries’ taken during an exoplanetary orbit period. The detection of an alien heat signature will have far-ranging implications, but even a null result, given 70 m aperture sensitivity, could also have broad social implications.application/pdfenghttps://creativecommons.org/licenses/by/3.0/530civilization biomarkerextraterrestrial civilizationsglobal warmingKardashev Type I civilizationsArticle