The idea of the planet X emerged from the attempts to explain the discrepancies in the orbits of Uranus and Neptune in the late nineteenth and early twentieth centuries. Initially, it was believed that it was a hypothetical planet that disturbed these orbits. Although Pluto’s discovery in 1930 was initially linked to this search, it was subsequently discovered that it was too small to explain the orbital anomalies. So, This enigmatic planet X (baptized with that name for being an unknown and, at the same time, the hypothetical tenth planetary body of the solar system), remained in the dark.
Now, a team of scientists has adopted A completely different approach to this story of cosmic detectives: Instead of seeking the reflected sunlight, they look for the thermal signal of the planet.
The story begins with an enigma in the exterior solar system. The scientists observed that small icy bodies called Kuiper belt, which orbit far beyond Neptune, seem to be grouped in unusual ways. Their orbits are aligned in patterns that should not exist by pure chance. The main and most tempting explanation? Planet X is gravitationally guiding these distant objects towards their strange orbits.
To achieve this gravitational influence, the planet X would be a true giant, with a mass of approximately 5 to 10 times that of the earth, orbiting between 400 and 800 times further from the sun than our planet. At such a huge distance, It would be incredibly dim and almost impossible to detect with traditional telescopes which are based on the detection of reflected sunlight.
This is where the new study, published in Arxiv, is approaching from an optics other than enigma. And when we say optics, it is literally. Led by Amos Chen, from the National University Tsing Hua, the team realized that looking for the thermal signal of this giant could be much more effective than looking for its reflected light. This is because, by duplicating the distance to the sun, lIn reflected light it becomes 16 times more dim (following what scientists call an inverse relationship of the fourth power). But thermal radiation, the heat that all objects emit naturally, only becomes 4 times more dim when duplicating the distance.
The researchers resorted to Akari data, a space telescope that the Japanese agency coordinates with NASA and that is responsible for the most sensitive study of the entire sky in distant infrared light, The perfect wavelength range to detect the thermal signal of a cold and distant planet. Unlike terrestrial telescopes, which are hindered by the Earth’s atmosphere, Akari could detect the faint thermal glow that the planet X should emit.
The authors focused their search in a specific region of the sky where, according to computer simulations, it was more likely to find it, based on the orbital patterns of Kuiper belt objects. They faced then The difficult task of distinguishing a planet of slow motion of the innumerable stars, galaxies and cosmic debris that populate this region.
However, they found a fairly elegant solution: planet X should seem stationary for a single day, but show a detectable movement for months. When comparing Akari’s observations taken at different times, They were able to identify objects with this specific type of movement, filtering at the same time cosmic rays, background galaxies and other false signs.
After this meticulous analysis, the researchers identified two candidates. Both objects appear in the planned location and emit the amount of infrared light that the theory suggests that the planet X should produce. While this does not constitute a definitive test, It represents the most promising track in the search for the hidden giant of our solar system.
These discoveries mark an important milestone, but the trip is not over. Candidates require monitoring observations with more powerful telescopes to confirm if they really move consistently with planet X or if they are impostorsperhaps background galaxies or other astronomical objects.
If confirmed, the discovery would revolutionize our understanding of the formation and evolution of our solar system. I would also demonstrate the power to think creatively about astronomical searches: sometimes, The best way to find something is not to look directly, but detect its heat.