Scientists have always been keen to understand how life started on Earth. Some theories claim it happened due to meteors, others say it happened due to volcanic eruptions around 4.5 billion years ago. All these answers, however, remain unverified. While these theories are still being discussed, a new study has now emerged that suggests oldest continents in our galaxy (Milky Way) may have arisen five billion years before Earth's. It has given rise to speculation that there may be multiple worlds in the Milky Way harbouring alien life even more advanced than our own.
A study detailing the new discovery has been published in the journal Research Notes of the American Astronomical Society.
Cardiff University astronomer Jane Greaves, who carried out the study, found that two exoplanets' continents may have arisen four to five billion years before Earth's.
"If life on another planet had a five-billion-year head start, it could potentially host life more evolved than us," Ms Greaves wrote in a study.
According to study carried out on Earth, continents form due to the movement of tectonic plates on a planet's surface. This happens because the rocks of the plates floats atop the molten magma, which remains in this state because of heat from radioactive elements, like uranium, thorium and potassium.
In her work, Ms Greaves analysed levels of uranium present in nearby stars, and combined the data with the ages of stars as measured by the Gaia satellite. The analysis gave her the timeframe when each of these stars became hot enough for plate tectonics to emerge.
She found that the first continents formed around nearby Sun-like stars a few billion years earlier than Earth's plate tectonics began.
This study on potentially habitable planets is crucial for future space missions. Ms Greaves hopes her work will be a stepping stone for future work that will analyse more such planets.
