Astronomers spot another alien world circling the nearest star to the sun

Back in January of 2020, astronomers discovered a potential super-Earth orbiting Proxima Centauri, the nearest star to the sun.

It was, at the time, the second planet spotted in the nearby planetary system.

Now, scientists may have come across a third planet in the clearly crowded region, according to a press release by the European Southern Observatory (ESO). 

A new planet in Proxima Centauri

“The discovery shows that our closest stellar neighbor seems to be packed with interesting new worlds, within reach of further study and future exploration,” stated João Faria, a researcher at the Instituto de Astrofísica e Ciências do Espaço, Portugal and lead author of the study published today in Astronomy & Astrophysics. 

The researchers, however, did not get very creative when naming the new planet: simply calling it Proxima d. The other two planets discovered in the system were called Proxima b and Proxima c.

Proxima d is just a quarter of the mass of Earth, making it the lightest exoplanet ever measured using the radial velocity technique. This technique consists of identifying tiny wobbles in the motion of a star, this time Proxima Centauri, created by an orbiting planet’s gravitational pull.

The researchers noted that Proxima d’s gravity is so small that it only causes Proxima Centauri to wobble at around 40 centimeters per second (1.44 kilometers per hour). Additional data suggest that the planet completes a full orbit of the star every five days at one-tenth of the distance between the Sun and Mercury.

Not hospitable

Unfortunately, it is located at about 2.4 million miles (4 million kilometers) away from its star, closer than its habitable zone, meaning it is not a good candidate for the presence of water. Hints of the planet's presence were picked up all the way back in 2020 during investigations of Proxima b, the first planet ever detected in the nearby planetary system.

However, it took observations made with ESPRESSO, an instrument on ESO’s telescope, to deduce that an actual planet was the cause of the spotted disruptions and not changes in Proxima Centauri itself. Now, researchers are hoping to use this tool to make even more discoveries. “This result clearly shows what ESPRESSO is capable of and makes me wonder about what it will be able to find in the future,” concluded Pedro Figueira, ESPRESSO instrument scientist at ESO in Chile.