The Physics Boy

The discovery of an Earth-sized planet orbiting around a cool red dwarf star

The discovery of an Earth-sized planet orbiting around a cool red dwarf star
Credit: NASA/JPL-Caltech

The Discovery

A team of astronomers utilizing robotic telescopes around the world has recently spotted a new planet which is Earth-sized and it is orbiting around a cool red dwarf star. This new exoplanet is named as SPECULOOS-3 b and is about 55 light-years from Earth and has approximately the same size as that of Earth. A distance of 55 light-years is considered closer to the universe’s cosmic scale.

The SPECULOOS-3 b is orbiting around its star quite fast as compared to Earth. This is because to complete one revolution around its star takes only 17 hours i.e. a year on that planet is only of 17 hours. The planet is however not rotating about its axis like Earth where we are having day and night. One side of it has a never-ending day and on the other side its a never-ending dark just like the Moon to Earth.

The discovery is done by Search for habitable Planets Eclipsing Ultra-cool Stars (SPECULOOS) located at the Paranal Observatory in the Atacama Desert of northern Chile, a project led by Michael Gillon at the University of Liège, Belgium. The project of SPECULOOS was started with a mission to observe Ultra-cool dwarf stars are scattered across the sky which take weeks to get a chance to detect transiting planets.

Gillon said:

‘‘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!’’

Our Milky Way has a collection of red dwarf stars. Almost more than 70% of the starts in our galaxy are M dwarfs which is also known as red dwarfs.

Red Dwarfs

Red dwarfs star are cool and dim as compared to Sun. However, they have high energy radiation especially early in their lives. So, if it has a planet orbiting around it keeps getting these high energy radiation. If we compare with Sun in terms of life span than Sun will burn for about 10 billion years before turning into hungry red giants and M dwarfs keep burning for 100 billion years or more.


The SPECULOOS-3 star has a very low temperature as compared to Sun. Its temperature is 1000s of degrees cooler than our Sun. It average temperature is about 4,760 F (2,627 C) which continuously strikes its planets with radiation due to which its planets has likely no atmosphere.

Image Credit: An artist’s impression of the SPECULOOS-3 system Lionel Garcia

A postdoctoral researcher at NASA’s Jet Propulsion Laboratory in Southern California named as Catherine Clark said:

“Though this particular red dwarf is more than a thousand times dimmer than the Sun, its planet orbits much, much closer than the Earth, heating up the planetary surface,”

This might be chance that SPECULOOS-3 b will be further observed by the James Webb Space Telescope for more data collection which includes a closer look at the atmosphere and its the surface mineralogy. The study of this near planet and Earth-sized will further help us understand the stellar neighborhood and our place in it.

James Webb Space Telescope
Image Credit: NASA

A planet discoverer at NASA Ames Research Center in Silicon Valley, Steve B. Howell said:

‘‘We’re making great strides in our study of planets orbiting other stars. We have now reached the stage where we can detect and study Earth-sized exoplanets in detail. The next step will be to determine whether any of them are habitable, or even inhabited’’

New planets are continuously being discovered and explored to understand is there any other habitable planet in our universe which may have life. This discovery of SPECULOOS-3 b s which is Earth-sized is a remarkable step in the field of astronomy.