🪐 Two candidates detected for Planet Nine!

For years, scientists have been scanning the icy outskirts of our Solar System for an unknown massive planet. The disturbances observed in the orbits of Kuiper belt objects suggest the presence of such a body, nicknamed Planet Nine. If it exists, this planet would be much more distant and massive than Pluto.

Traditionally, searches focused on sunlight reflected by the planet. A team led by Amos Chen has chosen an innovative approach by looking for its thermal signature. The heat naturally emitted by any object stands out better at great distances than reflected light, offering a more promising lead.


The researchers used data from AKARI, a Japanese space telescope specialized in far-infrared. This technology can detect the faint thermal glow of a planet as distant and cold as this one. The analysis focused on a precise area of the sky, predicted by simulations as the most likely location for Planet Nine.

Two potential candidates emerged from this meticulous study. Their position and infrared emission match theoretical expectations for Planet Nine. Although promising, these results require follow-up observations to confirm their nature. The discovery of such a planet would revolutionize our understanding of the Solar System's formation.

This innovative method illustrates how science sometimes progresses by taking unconventional paths. The quest for Planet Nine shows that the most effective solutions aren't always the most obvious ones.

Why is thermal signature more effective than reflected light?

Light reflected by an object diminishes rapidly with distance, following a mathematical law. In contrast, heat emitted by the object itself follows a slower decay, making it more detectable at great distances.

Infrared telescopes like AKARI are designed to capture this heat, however faint. This opens new possibilities for discovering celestial bodies too distant or too cold to be seen otherwise.

This thermal approach is particularly suited to the search for Planet Nine, located in a region where sunlight is extremely weak. It could also apply to the search for other objects at the Solar System's fringes.

How do Kuiper belt objects betray Planet Nine's presence?

Kuiper belt objects exhibit strangely aligned orbits, suggesting the gravitational influence of a massive body. This configuration is unlikely in a Solar System lacking such a planet.

Computer simulations show that a planet 5 to 10 times Earth's mass could explain these anomalies. Its orbit would be very distant, between 400 and 800 times the Earth-Sun distance, making it difficult to observe directly.

Studying these distant objects thus provides an indirect method to locate Planet Nine.