A planet less than a million years old is still being built right now

Astronomers have confirmed the youngest exoplanet we know about. It's called Elias 2-24 b, it's about 450 light-years away, and it's less than a million years old. Earth is around 4.5 billion years old, so this thing is a newborn.

The part I like is that it isn't finished yet. It's still pulling in gas and dust from the disk around its young star. So we're not really looking at a planet. We're looking at a planet while it's being built.

The evidence stacks up nicely. About ten years ago, ALMA in Chile imaged the dusty disk around the star and found a gap in it. Gaps like that were the main hint that a planet might be forming in there and sweeping up material as it grows. Then ESO's Very Large Telescope picked up a faint point of light sitting inside that gap. After that, the team, led by Diego Portales University in Chile, went back through older Keck Observatory data and found it there too. Three telescopes, one object, published in The Astrophysical Journal Letters.

It's a big planet, somewhere between two and four times the mass of Jupiter, and it orbits at almost twice the distance Neptune sits from our Sun. It also backs up the core accretion model, which is the idea that giant planets grow by piling material onto a core rather than collapsing all at once.

I grew up looking at artists' drawings of the early solar system. Now there's a real one to point at, 450 light-years away, still in progress.

Source: https://science.nasa.gov/universe/newfound-baby-planet-smashes-record-for-youngest-known-world/