Earth Detecting Earth: How Far Away Can We Detect Earth's Technosignatures?

If an extraterrestrial civilization existed with technology similar to ours, would they be able to detect Earth and evidence of humanity? If so, what signals would they detect, and from how far away? Researchers used a theoretical, modeling-based method, and this study is the first to analyze multiple types of technosignatures together rather than separately. The findings revealed that radio signals, such as planetary radar emissions from the former Arecibo Observatory, are Earth's most detectable technosignatures, potentially visible from up to 12,000 light-years away. Join Simon Steel, Deputy Director of the Carl Sagan Center, for a chat with lead author Sofia Sheikh about the research's findings and their implications for the search for technosignatures. (Recorded 13 February 2025.)