Once again, astronomers have been unsuccessful in their quest to find Planet Nine, a hypothetical world believed to be hidden deep behind an icy rock cloud well beyond the orbit of Neptune. The Astrophysical Journal published a report on Dec. 23, 2021, analyzing data from six years of observing with telescopes to look for evidence of Planet Nine in the southern sky.
The unsuccessful search does not invalidate the existence of the hypothetical planet, the researchers claim. Ultimately, the study only covers 10% to 20% of the planet’s available sky locations.
Planet Nine exists in the distinct possibility
As scientists, Konstantin Batygin and Michael Brown convincingly argued in 2016, the existence of a ninth planet in the solar system is a distinct possibility. Since it is located in the Kuiper Belt, astronomers have a sense that it is there. Exaggerated, inclined orbits and clustering behavior have been observed in over 30 of these objects to date.
According to Gizmodo, scientists have postulated a massive object — Planet Nine — as a possible explanation for this phenomenon. But the planet must be massive and heavy enough to work this way. An estimated five to ten times Earth’s size, 200 to 800 au from the Sun. Given the distances involved and the presumed dark nature of the planet, their failure to identify the object is not surprising.
“Is Planet Nine out there?” It doesn’t reflect much light and emits very little radiation. Other theories to explain the Kuiper Belt anomalies, such as a bowling-ball-sized black hole in the Oort Cloud or a large debris ring in the outer solar system, have failed to discover it in prior surveys with the Wide-field Infrared Explorer.
The Atacama Cosmology Telescope scanned space at millimeter wavelengths for the current hunt. The ACT telescope’s sensitivity makes it ideal for searching for a needle in a haystack. ACT, according to co-author and University of Pittsburgh astronomer Arthur Kosowsky, has two distinct characteristics.
“We have sufficient sensitivity to microwave-wavelength radiation to possibly detect Planet Nine’s thermal emission, and we have observed a wide swath of the sky where Planet Nine might be located,” Kosowski explained, as quoted in the report.
Planet Nine still missing in action after 87% survey of the Southern Sky
As reported by Live Science, more than 87% of the sky visible from the southern hemisphere was covered by Atacama Cosmology Telescope (ACT) observations between 2013 and 2019, with no sign of the ninth planet.
While this survey found no evidence of Planet Nine, additional millimeter telescope facilities, like the Simons Observatory in Chile’s Atacama Desert, will allow astronomers to narrow the search even more.