Astronomers reveal evidence for a hidden 'Planet Y' beyond Neptune

An artist’s illustration of a possible ninth planet in our solar system, hovering at the edge of our solar system. Neptune’s orbit is show as a bright ring around the Sun. (Image: ESO/Tom Ruen/nagualdesign/NASA)

The distant corners of our solar system might harbor a new planet. Astronomers have detected strange tilts in far-off Kuiper Belt objects, which indicate the presence of a hypothetical Planet Y.

What are the signs of Planet Y's presence?

Planet Y has not been seen directly, but its effect can be seen. Scientists analyzed about 50 icy bodies beyond Neptune and discovered unexplained orbital tilts. These tilts cannot be explained by passing stars or standard planetary formation models. Lead author Amir Siraj said the planet is likely smaller than Earth yet bigger than Mercury, orbiting far from the Sun, as reported by CNN.

The concept of hidden planets beyond Neptune is not new. Searches for Planet X began after Neptune’s discovery in 1846. Pluto was originally a contender but later reclassified as a dwarf planet because of its size. Planet Y differs from the previously proposed Planet Nine, which is thought to be five to ten times Earth’s mass and orbit much farther out.

How significant are the findings and simulations?
The observed tilt beyond roughly 80 times the Earth-Sun distance measures about 15 degrees. Computer simulations indicate that Planet Nine alone cannot account for this discrepancy. Siraj’s team suggests Planet Y orbits at 100 to 200 times the Earth-Sun distance with a tilt of at least 10 degrees relative to the known planets. Statistical analysis shows a 96 to 98 percent significance, strong but not yet definitive.

When could Planet Y be confirmed?
The Vera C. Rubin Observatory in Chile could provide decisive evidence. Its large digital camera will scan the entire sky every three days over a 10-year survey.  Astronomers hope it will uncover new objects and define if Planet Y really is there.

The hunt for Planet Y reminds scientists that our solar system still has secrets. If it's confirmed, this secret world would transform knowledge of planetary forces and the far reaches of our cosmic neighbourhood.