An “unexpected” space traveler challenges theories about the origin of the Solar System

Researchers have shown that a fireball from the edge of the Solar System It was probably made of rock, not ice. which challenges entrenched beliefs about how the Solar System formed.

Right at the edge of our solar system and halfway to the nearest stars is a collection of icy objects drifting through space, known as the Oort Cloud. Sometimes the passing of the stars pushes these icy travelers towards the Sun, and we see them as comets with long tails. Scientists have yet to directly observe any objects in the Oort Cloud, but anything detected so far coming from its direction has been ice.

Theoretically, the very foundation of understanding our early Solar System is built on the assumption that only icy objects exist in these outer reaches, and certainly nothing made of rock.

This changed last year, when an international team of scientists, stargazers, and professional and amateur astronomers led by Western meteorite physicists captured images and video of a rocky meteoroid streaking through the skies over central Alberta as a dazzling ball of fire. Since then, researchers have concluded that everything points to the object originating in full Oort cloud.

The results were published in the magazine Nature Astronomy.

“This discovery supports a totally different model of the formation of the solar system, which supports the idea that significant amounts of rocky material coexist with icy objects in the Oort cloud,” says Denis Vida, a postdoctoral researcher in meteorite physics. of the Western Ontario University. “This result is not explained by currently accepted models of the formation of the solar system. It’s a complete game changer.”

All previous rocky fireballs have come from much closer to Earth, so this body – which clearly traveled great distances – is completely unexpected. The advanced cameras of the Global Fireball Observatory (GFO), developed in Australia and managed by the University of Alberta, observed a rocky meteoroid the size of a grapefruit (about 2 kilos). Using the Global Meteor Network tools developed for the Winchombe bolide, the Western Ontario researchers calculated that it was traveling in an orbit normally reserved only for long-period icy comets from the Oort Cloud.

“In 70 years of regular fireball observations, this is one of the most peculiar ever recorded. It validates the GFO strategy established five years ago, which expanded the ‘fishing net’ to 5 million square kilometers of skies and brought together scientific experts from around the world,” said Hadrien Devillepoix, Research Associate at the Curtin University (Australia) and principal investigator of the GFO.

“Not only does it allow us to find and study precious meteorites, but it’s the only way to have a chance of capturing these rarer events that are essential to understanding our solar system.”

During your flight, the Alberta fireball descended much deeper into the atmosphere than icy objects in similar orbits and it broke apart just like a fireball spewing stony meteors, the necessary proof that it was, in fact, made of rock. By contrast, comets are basically fluffy snowballs mixed with dust that slowly vaporize as they approach the Sun. The dust and gases they contain form their characteristic tail, which can stretch for millions of kilometers.

We want to explain how this rocky meteoroid ended up so far away because we want to understand our own origins. The better we understand the conditions in which the solar system was formed, the better we will understand what it took for life to emerge,” says Vida.

“We want to paint a picture, as accurate as possible, of these early moments in the solar system that were so critical to everything that followed.”