Taiwan university researchers find ‘evidence’ of Planet Nine in infrared data

Software flagged 13 candidate pairs of infrared sources. After a manual check, only one remained. It had shifted 47.5 arcminutes across the sky over 23 years, about one and a half times the width of the full moon, potentially indicating the presence of a Neptune-sized planet in the Solar System.

Software flagged 13 candidate pairs of infrared sources. After a manual check, only one remained. It had shifted 47.5 arcminutes across the sky over 23 years, about one and a half times the width of the full moon, potentially indicating the presence of a Neptune-sized planet in the Solar System.

Terry Long Phan of National Tsing Hua University in Taiwan made the finding during his PhD research, working with colleagues in Taiwan, Japan and Australia.

Some researchers say that the unusual arrangement and orbital tilts of some trans-Neptunian objects (TNOs) could signal the presence of a yet-to-be-discovered planet.

The proposed planet’s elliptical orbit could extend to about 300 astronomical units (AU) from the Sun, making it at least 10 times farther away than Neptune. The planet, however, remains unconfirmed.

The problem is that sunlight would have to travel from the Sun to the planet and then back to Earth, making a Neptune-sized planet 10 times farther from the Sun about 100 times fainter in reflected light, not 10,000 times.

Researchers do not know exactly where to point a telescope to find Planet Nine.

The thermal emission of the planet would reach us directly from the planet. Using the infrared spectrum, Planet Nine would be much easier to detect than in visible light, rather than being subject to the same reduction in reflected sunlight. Thus, infrared telescopes in space are a promising way to search for it.

Phan analysed observational data obtained by two infrared surveys: IRAS, which was launched in 1983, and AKARI, which was launched in 2006.

At more than 300 AU, a planet would move slowly, appearing almost stationary within data from either survey. Between the two missions, however, it would have shifted slightly. Phan’s software searched through every infrared source and kept only those that had moved by roughly the expected amount.