In September 2026, scientists from Hokkaido University and their colleagues presented in the journal Science results that force us to take a fresh look at the very first steps of our planetary system. Samples from the asteroid Ryugu, delivered by the Japanese spacecraft Hayabusa-2, showed that the parent body of this celestial stone formed no later than two million years after the birth of the Sun — that is, at least 4,5653 billion years ago.
Ryugu is not a single, primordial object. It is rubble. A far larger body once existed. It collided with another, was destroyed, and over time the fragments came together again. It is precisely these fragments that were brought to Earth. Until now it remained unclear exactly when the original body appeared. A team of researchers, including Associate Professor Noriyuki Kawasaki, determined the age of the minerals in the samples using radioisotope methods and estimated the temperatures at which these minerals crystallized. The results were then checked against computer models of the thermal evolution of the parent body. The conclusion proved unambiguous: it arose in the very first moments of the Solar System's life.
This matters. Until now, analysis of meteorites similar to Ryugu indicated that their parent bodies formed later — roughly 2,2 million years or more after the beginning. Ryugu and the materials associated with it belong to an earlier generation. Such carbonaceous asteroids are rich in water and organics. It is believed that they may have delivered both water and the building blocks of life to the young Earth. Now it is clear: these materials already existed at the very start.
The picture that emerges is almost incredible. The Sun had only just flared into life. Around it swirled a disk of gas and dust. In the cold outer regions, the first solid bodies began to assemble almost instantly (by cosmic standards). Inside them, ice melted, water reacted with minerals, and complex compounds formed. Then came collisions, destruction, reassembly — and now the tiny asteroid Ryugu, less than a kilometer in diameter, has been carrying within itself for billions of years the chemical memory of those very first processes.
We live in a world where a piece of stone brought from a distance of hundreds of millions of kilometers allows us to peer into an era when there were as yet no planets in the familiar sense, nor even a fully formed Solar System. Everything turned out to be connected with astonishing precision: the radioactive decay of short-lived isotopes, heat, water, organics, collisions — and ultimately the conditions under which life was able to arise on one of the planets. Ryugu simply kept this story in silence until Hayabusa-2 opened it for us.
