NASA scientists have just discovered the youngest fully formed exoplanet ever detected, using NASA’s Kepler Space Telescope and its extended K2 mission. Dubbed K2-33b, this newborn exoplanet may help better understand how planets form.

The planet, K2-33b is a bit larger than Neptune and whips tightly around its star every five days. The planet is just 5 to 10 million years old, making it as one of the very few newborn planets found to date.

“Our Earth is roughly 4.5 billion years old. By comparison, the planet K2-33b is very young. You might think of it as an infant,” said lead researcher Trevor David from California Institute of Technology (Caltech) in the US.

Planet formation is a complex and tumultuous process that remains shrouded in mystery. Astronomers have discovered and confirmed roughly 3,000 exoplanets so far.

However, nearly all of them are hosted by middle-aged stars, with ages of a billion years or more.

 “The newborn planet will help us better understand how planets form, which is important for understanding the processes that led to the formation of Earth,” said co-author Erik Petigura from Caltech.

The first signals of the planet’s existence were measured by the Kepler telescope’s camera, which detected a periodic dimming of the light emitted by the planet’s host star, a sign that an orbiting planet could be regularly passing in front of the star and be blocking the light.

Infrared measurements from NASA’s Spitzer Space Telescope showed that the system’s star is surrounded by a thin disk of planetary debris, indicating that its planet-formation phase is wrapping up. Planets form out of thick disks of gas and dust, called protoplanetary disks that surround young stars.

“Initially, this material may obscure any forming planets, but after a few million years, the dust starts to dissipate,” said co-author Anne Marie Cody, from the NASA’s Ames Research Centre.

A surprising feature in the discovery of K2-33b is how close the newborn planet lies to its star. The planet is nearly 10 times closer to its star than Mercury is to our sun, making it hot.

Astronomers aren’t sure how planets end up so close to their stars. Some think it takes millions of years for them to migrate into such a tight orbit. But K2-33b’s young age is proof that can’t always be the case.

K2-33b could have migrated therein a process called disk migration that takes hundreds of thousands of years. Or, the planet could have formed “in situ” — right where it is, researchers said. The discovery of K2-33b, therefore, gives theorists a new data point to ponder.

“The question we are answering is: Did those planets take a long time to get into those hot orbits or could they have been there from a very early stage? We are saying, at least in this one case, that they can indeed be there at a very early stage,” David noted in a paper appeared in the journal Nature.

The findings were published in the journal Nature.