Is it plausible to imagine a tyrannosaur on Trappist-1e, a triceratops on Proxima Centauri b, or a quetzalcoatlus on Kepler 1047c? According to astronomers at Cornell University, these scenarios may not be as far-fetched as they seem. They believe that 'fingerprinting' the conditions that allowed dinosaurs to thrive on Earth, particularly atmospheric oxygen abundance, could be the key to discovering life on exoplanets.
Searching for Life Through Chemical Signatures
The study of Earth's evolution over the past 540 million years suggests that finding chemical signatures in the atmosphere of dinosaur-era Earth-like planets could be more straightforward. These signatures are crucial in our quest to unearth life on other planets.
Identifying Key Biosignatures
Notably, two pairs of biosignatures - oxygen and methane, and ozone and methane - were particularly prominent on Earth between 100 and 300 million years ago, a period when oxygen levels were much higher than they are now. Lisa Kaltenegger, director of the Carl Sagan Institute (CSI), notes that the 'light fingerprint' of modern Earth has been our go-to model for identifying potentially habitable planets, but the Earth of the past may offer even more telling signs of life.
Oxygen Levels on Earth: A Key Factor
Over the past 400 million years, oxygen levels on Earth have generally remained within the 'fire window' of carbon, ranging between 16 and 35 percent. This was the window that allowed fires to happen and, at its peak (around 30 percent approximately 300 million years ago), it is hypothesized to have enabled the emergence of large, complex creatures like dinosaurs.
Extraterrestrial Life Hunting: Looking for Dinosaur-like Planets
So far, astronomers have discovered around 40 rocky exoplanets in habitable zones where oceans might be present. Analyzing these exoplanets' atmospheres is a challenging task, pushing the limits of the James Webb Space Telescope's capabilities. Eisenhower, knowing what to look for is equally important. As per the researchers' models, planets similar to the Phanerozoic Earth seem to be promising targets in the cosmic search for life.
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