English: "A concept image illustrating various types of technosignatures described in this paper, including atmospheric, optical, and radio technosignatures. Atmospheric technosignatures may include obviously artificial molecules such as sulfur hexafluoride (SF6) in addition to common molecules expected for an inhabited terrestrial planet, such as oxygen (O2), carbon dioxide (CO2), and methane (CH4). The top left inset shows the absorption cross-sections of S6 [7]. Optical technosignatures include highly collimated laser pulses that can outshine the host star at narrow wavelengths (i.e., Optical SETI). The middle left inset illustrates the narrow power distribution of an optical (green) laser pulse. Active radio beacons or passive radio leakage from the planetary surface, orbit, or elsewhere in the stellar system would be recognizably artificial (i.e., traditional SETI). The bottom left inset illustrates the narrow distribution of power versus frequency anticipated for an artificial radio signal. Additional potentially detectable technosignatures in this planetary system include artificial lighting on the planetary nightside [e.g., 8], recognizable spectral breaks from solar arrays on the planet’s moon [e.g., 9], and anomalous transit signatures from the orbiting habitats and satellite arrays [e.g., 10, also see Section 6]. (For interpretation of the references to color in this figure legend, the reader is referred to the web version of this article.)"