Our atmosphere holds key to alien life: Study

◗

London, Feb. 20: Scientists have explained how Earth’s atmosphere evolved over time, an advance that may hold the key to detecting life on planets beyond our solar system.

According to the study, published in The Astrophysical Journal, how Earth’s atmosphere evolved corresponds to the appearance of different forms of life.

The team, led by researchers at the University of St Andrews in the UK, studied different geological epochs from Earth’s history, modelling the atmospheres around different stars, bigger and smaller than our Sun.

The researchers found that a planet’s star type is an important factor in how an exoplanet’s atmosphere develops and how detectable signs of life or biosignatures will be.

T he study focused on Earth’s atmosphere at four distinct points in history: before microbes ( 3.9 billion years ago), after microbes and the first rise of oxygen ( 2 billion years ago), during the second rise of oxygen ( 800 million years ago), and Earth as it is today.

At each of these points, oxygen, methane and carbon dioxide were in drastically different abundances.

Researchers have found that a planet’s star type is an important factor in how an exoplanet’s atmosphere develops and how detectable signs of life or biosignatures will be in the future

The new findings on how life evolves in different atmospheres could lay the foundation for scientists to interpret early biosignatures and signs of life on exoplanets.

“We expect to find a myriad of exoplanets beyond even our wildest imagination. Even looking back at our own planet, the atmosphere has changed dramatically many times,” said Sarah Rugheimer, astronomer at University of St Andrews.

“By looking at the history of Earth and how different host star light would interact with a planet’s atmosphere, we can start to create a grid of models to help us understand future observations,” said Rugheimer.

Varied cloud cover and surface features such as oceans and continents were also factored in during the study to see how these affected the models.