The discovery in 1995 of a planet orbiting a Sun-like star outside our solar system opened a new era in astronomy and later contributed to part of the 2019 Nobel Prize in Physics. Since that finding researchers have catalogued more than 4,000 exoplanets, including some that are Earth-like and could, in principle, harbor life.
Astronomers aim to identify observable features that would show life is, or once was, present on another world. In recent years the search has focused on biosignatures: chemicals, patterns or other signs that indicate biological activity. Establishing reliable biosignatures across interstellar distances remains difficult and is a central research challenge.
Scientists also consider technosignatures, traces of technology or large-scale engineering that advanced civilizations might leave. Technosignatures could, in some cases, be easier to detect than subtle biosignatures. A NASA grant now supports astrophysicist Adam Frank in work to define what technological traces might look like and how they could be seen at interstellar distances; part of this work is a careful comparison of evidence from simple life and from technological societies.
Teams continue to develop detection methods, defining which signals to search for and scanning the growing exoplanet catalog for those signals. At present it is unclear which approach will yield the first convincing evidence, or whether either path will provide definitive proof of life beyond Earth. Adam Frank discusses these topics in a video based on material from the University of Rochester, and the report appeared on Futurity.
Difficult words
- exoplanet — planet that orbits a star outside our solar systemexoplanets
- biosignature — chemical or pattern that shows biological activitybiosignatures
- technosignature — trace or sign of technology from advanced civilizationtechnosignatures
- establish — to show or prove something is trueEstablishing
- observable — able to be seen or measured from a distance
- definitive — final and strong evidence that settles a question
Tip: hover, focus or tap highlighted words in the article to see quick definitions while you read or listen.
Discussion questions
- Which approach do you think is more likely to find life first, biosignatures or technosignatures? Explain your reasons.
- What practical or technological challenges make detecting signs of life across interstellar distances difficult? Give examples based on the article.
- If convincing evidence of life beyond Earth were found, how might that change scientific research or public opinion?
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