An ‘unexpected’ space traveler challenges theories about the origin of the solar system

Western researchers have shown that a fireball that originated on the outskirts of the solar system was likely made of rock, not ice, challenging long-held beliefs about the formation of the solar system.

Just at the edge of our solar system and halfway to the nearest stars is a collection of icy objects cruising through space known as the Oort Cloud. Passing stars sometimes push these icy travelers towards the sun, and we see them as long-tailed comets. Scientists have yet to directly observe any objects in the Oort cloud, but everything detected so far from its direction has been ice.

Theoretically, the very basis for understanding the beginnings of our solar system rests on the fact that only icy objects exist within these confines and certainly nothing rock.

That changed last year when an international team of scientists, stargazers and professionals and amateur astronomers led by Western Meteor physicists captured images and video of a rocky meteoroid streaking across the sky over central Alberta as a dazzling fireball. Researchers have since concluded that all signs point to the object’s origin being right in the middle of the Oort cloud.

The findings were published in natural astronomy.

“This discovery supports an entirely 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,” said Denis Vida, Western postdoctoral researcher in physics. meteors. “This result is not explained by the currently favored models of solar system formation. This is a complete game-changer.”

All previous rocky fireballs have arrived from much closer to Earth, which makes this body – which has clearly traveled great distances – completely unexpected. State-of-the-art cameras from the Global Fireball Observatory (GFO), developed in Australia and operated by the University of Alberta, observed a rocky meteoroid the size of a grapefruit (about 2 kg). Using Global Meteor Network tools, developed for the Winchombe fireball, Western researchers calculated that it was moving through an orbit typically reserved for icy long-period comets in the Oort Cloud.

“In 70 years of regular fireball sightings, this is one of the most singular on record. It validates the GFO strategy established five years ago, which widened the ‘fishing net’ to 5 million square kilometers of sky, and brought together expert scientists from around the world,” said Hadrien Devillepoix, research associate at Curtin University, Australia, and GFO Principal Investigator.

“This not only allows us to find and study valuable meteorites, but it’s the only way to have a chance of catching those rarer events that are critical to understanding our solar system.”

During its flight, the Alberta fireball descended much deeper into the atmosphere than icy objects in similar orbits and broke up exactly like a fireball dropping stony meteorites – the necessary proof that he was, in fact, made of rock. Conversely, comets are essentially fluffy snowballs mixed with dust that slowly vaporize as they approach the sun. The dust and gases they contain form the distinctive tail that can stretch for millions of miles.

“We want to explain how this rocky meteoroid got so far away because we want to understand our own origins. The better we understand the conditions under which the solar system formed, the better we understand what was needed to spark life.” , Vide said.

“We want to paint as faithful a picture as possible of those first moments of the solar system who were so critical of everything that happened after.”