The solar system was completely swallowed up 14 million years ago

Imagine a massive wave of dust consuming the solar system and dimming our view of the night sky from here on Earth. As it turns out, it’s not far-fetched at all. Astronomers have found evidence of our solar system being engulfed by a huge wave of gas and dust millions of years ago.

The Milky Way is known to contain waves of stars, gas and dust that move with a smooth up-and-down motion. One of the closest is the Radcliffe wave, which has a breadth of nearly 9,000 light-years and is just 400 light-years away from our solar system.

However, a team of researchers have found that the Radcliffe wave used to be much closer to us and crossed our solar system between 11 million and 18 million years ago. Efrem Maconi at the University of Vienna and his colleagues made this discovery by using data from the Gaia space telescope which has tracked billions of stars in the Milky Way. The team used the data to identify newly formed star clusters within the Radcliffe wave, along with the associated dust and gas clouds that gave rise to them.

The Radcliffe WaveCreative Commons

Researchers tracked the orbits of the clouds back in time to determine their historical locations. They were also able to calculate the historic path of the solar system by looking back 30 million years through which they discovered that the solar system and the wave came very close to each other between 15 and 12 million years ago.

While pinpointing the exact timing of this event is challenging, the team estimates that Earth was within the wave around 14 million years ago.

Earth’s galactic environment would have been a lot darker 14 million years ago than it is today, as we currently live in a relatively empty region of space. According to Maconi, being in a “denser region of the interstellar medium” would have caused the light from distant stars to be dimmed. “It’s like being in a foggy day,” he told New Scientist.

This close encounter may have also left evidence in the geological record of Earth in the form of deposited radioactive isotopes in the crust. However, this would be hard to measure considering how long ago it happened, Maconi said. The crossing appeared to have occurred during Earth’s cooling period, called the Middle Miocene, which also marked significant changes on global ecosystems.

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