Earth is a pretty unique place. Thanks to its location in the habitable zone, life as we know it was able to grow and thrive on the planet. However, in our brief time exploring the surrounding cosmos for signs that we are not alone, we have consistently come up empty-handed.
Astrobiologists are concerned with the origin and dispersion of life throughout the universe, and since Earth is the only place we know where life has emerged, the Blue Planet and its features have thus far guided our attempts to spot life lurking somewhere other than our home. By predicting what Earth could look like in the next 1,000 years, researchers may be able to hone in on possible signs of life throughout the cosmos.
Searching for Molecular Evidence of Intelligent Life
One way astrobiologists have sought to identify life on other worlds has been by spotting biosignatures. These are the molecular or chemical byproducts of living systems. For instance, if we detected oxygen in the atmosphere of a distant planet, we might suspect that some living process could be its source since life fills Earth's atmosphere with oxygen.
One issue with the biosignature approach is that some unknown non-living process could be responsible for whatever chemical 'biosignature' we detect. For this and other reasons, spotting something more unambiguous, such as a signal from an advanced civilization's technology, has also been on the radar.
