Astronomers have confirmed a planet that is less than one million years old — younger than any previously confirmed world. Named Elias 2-24 b, it is still embedded in the gas-and-dust disc where planets are born.

The discovery is important because giant planets are expected to take time to assemble. Elias 2-24 b appears to be roughly Jupiter-mass and orbits about 55 astronomical units (AU) from its young star, much farther out than Jupiter's 5.2-AU orbit around the Sun.

What is a protoplanetary disc?

Young stars are often surrounded by rotating discs of gas and dust left over from star formation. Tiny solid particles can collide and stick together, gradually building larger bodies. Growing planets can also gather gas and interact gravitationally with the surrounding disc.

How can a planet carve a gap?

A sufficiently massive growing planet can disturb nearby disc material through gravity. Its interaction with gas and dust can contribute to a ring-like gap around its orbit. Such gaps are valuable clues — but they are not proof by themselves that a planet exists.

How was Elias 2-24 b found?

Astronomers had already observed a prominent gap in the Elias 2-24 disc with the Atacama Large Millimeter/submillimeter Array (ALMA). Later observations revealed a faint point of light in the gap. The crucial evidence came from combining observations across time.

Researchers reanalysed archival coronagraph observations from the W. M. Keck Observatory taken in 2018 and 2020. Tracking the faint source's motion helped show that it behaved as an object orbiting the young star rather than a stationary background source or an imaging artefact.

What does a coronagraph do?

A star can be millions or billions of times brighter than a nearby planet. A coronagraph suppresses or blocks much of the star's glare, allowing instruments to search for much fainter objects close to it. It is similar in principle to shielding your eyes from a bright lamp so you can see something dim beside it.

Why is the planet's age surprising?

NASA notes that current models can require roughly five million years to form a Jupiter-size planet at Jupiter's distance, with formation potentially taking longer farther from a star. Elias 2-24 b is less than one million years old and lies roughly 55 AU from its star, so its existence provides a demanding test for those models.

This does not mean established planet-formation physics has been disproved. Instead, observations like this help scientists determine which mechanisms dominate under different disc conditions and how quickly material can be assembled.

Two broad routes to giant planets

One major model, core accretion, begins with solids building a sufficiently massive core that later captures a large gaseous envelope. Another possibility, gravitational instability, involves parts of a massive disc collapsing more directly under their own gravity. Young, distant giant planets can help astronomers test when each pathway may be plausible.

Common misconception: a disc gap proves there is a planet

It does not. Disc structures can have more than one possible cause. Elias 2-24 b became convincing because researchers combined the gap, a directly detected faint source and evidence that the source moved consistently with an orbit.

A lesson about how science works

The confirmation also demonstrates the value of telescope archives. Observations collected years earlier can become scientifically powerful when researchers develop better processing techniques or combine them with newer measurements. Science advances not only by collecting new data, but also by asking new questions of existing data.

Key takeaways

  • Elias 2-24 b is less than one million years old, making it the youngest confirmed planet known.
  • It is roughly Jupiter-mass and orbits about 55 AU from its star.
  • It remains embedded in the protoplanetary disc where it formed.
  • Archival Keck observations helped confirm its orbital motion.
  • Its extreme youth and wide orbit make it a valuable test of giant-planet formation models.

Frequently asked questions

How far is Elias 2-24 from Earth?

The system is roughly 450 light-years away.

Is Elias 2-24 b habitable?

It is a very young giant planet, not an Earth-like world. The discovery is important primarily for understanding how planets form.

What is an astronomical unit?

One AU is approximately the average Earth–Sun distance. Jupiter orbits at about 5.2 AU, while Elias 2-24 b is roughly 55 AU from its star.

References

  • NASA Science, “Newfound ‘Baby’ Planet Smashes Record for Youngest Known World”, 16 September 2026.
  • The Astrophysical Journal Letters, research paper reporting the confirmation of Elias 2-24 b.