Astronomers Find the Youngest Known Planet

Astronomers this week confirmed the youngest known planet ever discovered — a Jupiter-sized world called Elias 2-24 b that is less than one million years old. In cosmic terms, this planet is a newborn — the universe is 13.8 billion years old, making this planet approximately 0.007% of the age of the cosmos.

The planet orbits a young star in the Ophiuchus constellation, approximately 400 light-years from Earth. Both the star and its planet are still surrounded by a thick disc of gas and dust — the raw material from which planets form. This disc, visible through powerful telescopes, is actively feeding the growing planet, adding mass as material spirals inward under the pull of gravity.

Watching a planet this young is like watching a construction site from space — you can see the scaffolding, the raw materials, and the emerging structure all at once. Most of the 5,700 exoplanets discovered so far are fully formed worlds, billions of years old. Elias 2-24 b is different: it is still under construction.

The confirmation required years of observation and sophisticated analysis. The planet was first suspected in 2020 when astronomers noticed a gap in the dust disc around the star — a gap that could only be explained by a large body sweeping up material as it orbited. Subsequent observations with the ALMA radio telescope array in Chile confirmed the planet mass, orbit, and age.

The discovery of Elias 2-24 b provides a rare opportunity to test our theories about how planets form — theories that, until recently, were based largely on inference rather than direct observation.

The leading model of planet formation — called the "core accretion" model — proposes that planets begin as tiny grains of dust in the disc of material around a young star. These grains collide and stick together, gradually building larger and larger bodies. Over millions of years, the growing object accumulates enough mass for its gravity to attract gas from the surrounding disc, eventually becoming a gas giant like Jupiter — or, given more time and different conditions, a rocky planet like Earth.

The process is surprisingly inefficient. Only a tiny fraction of the material in a protoplanetary disc ends up in planets — the rest is blown away by the star radiation, falls into the star, or drifts into interstellar space. Our own solar system used approximately 1% of the original disc material. The rest is gone.

Elias 2-24 b is massive — approximately five to ten times the mass of Jupiter. Its size relative to its young age challenges some aspects of the core accretion model, which predicts that building a planet this large should take longer. Alternative models — including gravitational instability, where sections of the disc collapse directly into planet-sized objects — may better explain how such a massive planet formed so quickly.

The debate is ongoing, and Elias 2-24 b will be a key test case. For the first time, astronomers can watch the process unfold rather than trying to reconstruct it from the finished product.

Elias 2-24 b is valuable not just for what it is but for what it teaches us about our own world.

Earth formed approximately 4.5 billion years ago from the same kind of dust disc that surrounds Elias 2-24 b star. The conditions were similar — a young star, a spinning disc of gas and dust, and the slow accumulation of material into planets. By studying Elias 2-24 b, astronomers are effectively looking at a snapshot of what our own solar system looked like in its earliest stages.

The comparison is illuminating. Earth was not always the temperate, ocean-covered world we know today. In its first few hundred million years, it was a hellscape — a molten ball of rock bombarded by asteroids, with no atmosphere, no water, and no possibility of life. The young Earth would have been unrecognisable to anyone standing on its surface today (assuming they could survive, which they could not).

Understanding how planets transition from this chaotic beginning to the stable, life-supporting environments we see today is one of the biggest questions in planetary science. Elias 2-24 b represents the very beginning of this process — the moment when a planet first emerges from its natal disc and begins its long journey toward whatever it will become.

Will Elias 2-24 b develop moons? Will it have rings like Saturn? Will smaller, rocky planets form closer to its star — planets that might one day support life? These questions cannot be answered yet. But the fact that we can ask them — about a planet 400 light-years away — is itself remarkable.

Perhaps the most profound aspect of the Elias 2-24 b discovery is what it tells us about the universe itself: creation is not over. It is happening right now.

We tend to think of the universe as a finished product — stars in their places, planets in their orbits, everything settled and stable. But the universe is dynamic. New stars are being born in stellar nurseries throughout our galaxy. New planets are forming around those stars. And somewhere, right now, the raw ingredients of a world that does not yet exist are coming together in a disc of spinning dust.

This is happening on scales we can barely comprehend. The Milky Way alone contains approximately 200 billion stars. Current estimates suggest there are more planets than stars — meaning our galaxy contains hundreds of billions of worlds. Most of them formed billions of years ago. But some are forming right now — and Elias 2-24 b is one we can actually see.

For humanity, this knowledge is both humbling and inspiring. Humbling because it places our world — our entire civilisation, our history, our achievements — in a context so vast that it defies comprehension. And inspiring because it shows that the universe is not winding down but continuing to create — that the process that made Earth and made us is still at work, right now, 400 light-years away.

A new world is being born. We are watching it happen. And somewhere in the future — millions of years from now — that world will be complete. What it will become, we cannot know. But the fact that we are here to witness its beginning is, in its own way, extraordinary.