Scientists found that our planet’s early atmosphere was as toxic as current Venus, as gases leaked from the ocean of magma during Earth’s evolution.It is possible that a Mars-sized object collided with young Earth in an effect that released enough energy to melt the entire mantle of the early planet – the layer between the core and the crust – and turn it into magma.
This massive event stripped most of Earth’s atmosphere at the time, to be replaced by carbon dioxide with little nitrogen – very similar to the atmospheric composition of Venus today, and similar to Mars.
These results come from a study by Paolo Souci and his team at ETH Zurich in Switzerland, whose paper, published in Science Advances on Wednesday, examined “the ocean of Earth’s magma and its early Venusian atmosphere.”
To understand Earth’s atmosphere early on, the team set out to recreate these conditions by floating a small piece of rock over a gas jet, then melting it down using a 1900 ° C laser.
“This little molten marble that floats at 2,000 degrees is a kind of miniature Earth in its molten state,” Susi told New Scientist.
By using different gases in the plane to suspend a chunk of molten rock, the researchers recreated varying atmospheric conditions, allowing them to see which of them most closely matched samples from the mantle and the geological record.
The team found that once the atmosphere released from Earth’s magma ocean cooled, it would “resemble the present planet Venus”. This, they say, indicates that the current differences between Earth’s atmosphere and Venus reflect what happened after the two planets formed.
Our planet is large enough that gravity keeps its atmosphere in place, unlike Mars, while Earth’s position in the solar system also makes it cool enough compared to Venus.
This means that, unlike Venus, water remains in liquid form on Earth’s surface and can absorb carbon dioxide from the atmosphere to prevent the planet from warming up – and most importantly, creating the conditions necessary to support and preserve life.