The uncertainty of science: Scientists have detected faint evidence that suggests the existence of a Neptune-sized exoplanet circling the sunlike star Alpha Centauri A.

After analyzing 100 hours of data gathered by NEAR in May and June of 2019, the scientists detected a thermal fingerprint in the habitable zone of Alpha Centauri A. The signal potentially corresponds to a roughly Neptune-size world orbiting between 1 and 2 astronomical units (AU) from the star, study team members said. (One AU, the average Earth-sun distance, is about 93 million miles, or 150 million kilometers.)

But that planet has not yet been confirmed, so it remains a candidate for now.

This result is very uncertain at this moment, so we should constrain our enthusiasm. If true, however, it would signal the possibility of more exoplanets circling the stars of the nearest stellar system. Alpha Centauri is actually three stars, a binary of two sunlike stars circled at great distance by the red dwarf Proxima Centauri. Scientists already think there are exoplanets circling Proxima, with one about the size of Earth.

What makes this particular interesting, if true, is that the exoplanet was detected not by the slight wobble its gravity caused in the star, or by a transit across the face of the star, but by its own light. If the detection is real, this would be I think the first time that an exoplanet has been seen directly, even if that detection comprises a few tiny pixels of light.