Find Us


SPECULOOS-3 b: Astronomers find new Earth-sized exoplanet about 55 light-years away

An artist’s concept of the exoplanet SPECULOOS-3 b orbiting its red dwarf star. The planet is as big around as Earth, while its star is slightly bigger than Jupiter – but much
An artist’s concept of the exoplanet SPECULOOS-3 b orbiting its red dwarf star. The planet is as big around as Earth, while its star is slightly bigger than Jupiter – but much Copyright NASA/JPL-Caltech
Copyright NASA/JPL-Caltech
By Roselyne Min with EBU/RTBF
Published on
Share this articleComments
Share this articleClose Button
Copy/paste the article video embed link below:Copy to clipboardCopied

The research team plans to study the exoplanet’s surface using NASA's James Webb Space Telescope.


A group of scientists at the University of Liège in Belgium recently spotted an Earth-sized planet orbiting an ultra-cool red dwarf.

The new exoplanet is roughly 55 light-years from Earth, which is extremely close on the cosmic scale, according to the research team.

“It is around a very small, very close star,” said Michael Gillon, an astronomer at the University of Liège who leads the SPECULOOS project.

Destined to be the last stars to burn when the universe grows cold and dark, red dwarf stars are also the dimmest stars and cooler than our Sun.

They make up 70 per cent of the stars in the Milky Way but are largely unexplored due to their low luminosity.

The exoplanet SPECULOOS-3 b orbits around a star called SPECULOOS-3 which was seen by different observatories from 2021 to 2023.

The research team says the star is about the size of Jupiter and twice as cold as the Sun.

It has an average temperature of approximately 2,627°C, while the surface of the sun has a temperature of 5,500°C, with its core topping 15 million°C.

Ultra-cool dwarf stars are scattered across the sky so it can take weeks to get a good chance to detect transiting planets, using robotic telescopes around the world.

The SPECULOOS (Search for Planets EClipsing ULtra-cOOl Stars) project was set up to research ultra-cool dwarf stars. In February 2017, the team discovered the first Earth-sized red dwarf star, TRAPPIST-1, and its seven-planet system in our galaxy.

“We named this star Speculoos 3, because the project that found it, our project, is called SPECULOOS, in reference to Belgium, of course,” said Gillon.

‘‘We designed SPECULOOS specifically to explore nearby ultra-cool dwarf stars in search of rocky planets. With the SPECULOOS prototype and the crucial help of the NASA Spitzer Space Telescope, we discovered the famous TRAPPIST-1 system. That was an excellent start,’’ Gillon wrote in a press release published by NASA.

‘Never-ending days and nights’

Despite its lower temperature, SPECULOOS-3 bombards its planet with intense radiation, likely stripping away any atmosphere. Researchers believe it’s unlikely that there’s any life on the planet.

“There is no atmosphere for liquid water to exist and liquid water is thought to be one of the essential elements for life, so this planet is clearly not habitable or inhabited,” said Gillon.

“But it is nevertheless an important step towards the study of habitable planets because we are also looking for and detecting this type of planet around other stars”.

An orbit around the star, a year on SPECULOOS-3 b, takes about 17 hours, according to NASA, with never-ending days and nights as the rocky planet is believed to be tidally locked.

“This planet is rocky and very close to its star, and we think that it always has the same face turned towards its star. We have a perpetual day side and a perpetual night side,” said Gillon.

Like the Moon does towards Earth, SPECULOOS-3 b may have a fixed face towards its star.


The research team plans to study the surface composition of the dayside using NASA's James Webb Space Telescope.

“We’re going to be able to study the surface composition of the day side, thanks to the James Webb Space Telescope, and learn more about this planet, which makes it quite unique, because it’s the first time we’ll be able to do this kind of study on a planet as small and as similar to Earth,” said Gillon.

For more on this story, watch the video in the media player above.

Video editor • Roselyne Min

Share this articleComments

You might also like