A group of scientists has come up with 5 models representing key points of our planet’s evolution such as chemical snapshots through geological eras. These can be used as spectral templates in the search for similar planets in distant solar systems with the help of powerful next-generation telescopes.
The models can be used as spectral temples to search the cosmos for exoplanets similar to Earth.
“These new generations of space- and ground-based telescopes coupled with our models will allow us to identify planets like our Earth out to about 50 to 100 light-years away,” explained Lisa Kaltenegger, associate professor of astronomy and director of the Carl Sagan Institute.
Using our own planet as a key factor, scientists were able to model five distinct eras of Earth to provide a template for how we can characterize a potential exo-Earth, from a young, prebiotic Earth to our modern world.
The models also allow astronomers to explore at what point in the evolution of Earth a distant observer could identify life on distant ‘pale blue dots’ in the universe and other worlds like them.
Kaltenegger and his team created atmospheric models that coincide with the Earth of 3.9 billion years ago of years, a prebiotic Earth when carbon dioxide densely covered the young planet. A second recoil model chemically shows an oxygen-free planet, an anoxic Earth, dating back 3.5 billion years. Three other models reveal the increase of oxygen in the atmosphere from a concentration of 0.2% to modern levels of 21%.
The researchers explained that our planet and the air we breathe “changed drastically since Earth formed 4.5 billion years ago.”
The new research paper speaks of how astronomers that are trying to find worlds like ours, could detect young to modern Earth-like planets in transit, all with the help of our own planet’s history as a kind of template.
The new study explains that when looking at the history of our planet, the exact timeline increased oxygen and its abundance is unclear. Nonetheless, if scientists are able to find distant alien worlds with around one percent of current oxygen levels, researchers will start finding emerging biology, ozone, and methane, which will allow them to compare it to Earth’s age templates.
The researchers reveal how our transmission spectra reveal atmospheric characteristics, which would display a remote observer (an alien studying Earth) that our planet had a biosphere about 2 billion years ago.
This means that forthcoming telescopes like the James Well SPAce Telescope which is set to launch in March 2021, and the Extremely Large Telescope in Antofagasta, Chile could revolutionize our hunt for Earth-like exoplanets since the telescopes would allow astronomers to observe the transit of a distant world in front of its star, which would reveal its atmosphere in unprecedented ways.
“Once the exoplanet transits and blocks out part of its host star, we can decipher its atmospheric spectral signatures,” Kaltenegger revealed.
Using Earth’s geologic history as a key, we can more easily spot the chemical signs of life on the distant exoplanets.”