Planet Nine: Is the search for this elusive world nearly over?

Deep in the outer reaches of the solar system — so far away from the known planets that the sun would barely be distinguishable from a nearby star — a massive, icy world may be lurking in the shadows, waiting to be discovered by humanity. 

And the day that we finally find this elusive planet may be coming soon, thanks to a state-of-the-art telescope that will begin scanning the sky next year.

The solar system has eight official planets: Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus and Neptune. But in recent years, astronomers have proposed that a ninth world, imaginatively nicknamed "Planet Nine," could be hiding in the far reaches of our cosmic neighborhood.

And no, we're not talking about Pluto, which was demoted from full planetary status to "dwarf planet" in 2006. Instead, scientists believe Planet Nine is a gas or ice giant billions of miles farther out than the rest of the planets. If it exists, it could also rewrite our understanding of the solar system's origins and evolution.

Related: How long would it take to reach Planet 9, if we ever find it? 

Astronomers have predicted how big this hypothetical world could be, how far away it could lie and even where it should be in its orbit around the sun. Yet actually finding Planet Nine, sometimes called Planet X, has eluded scientists for nearly a decade.

But the hunt for the solar system's potential ninth planet may soon be coming to a close. With the opening of the groundbreaking Vera C. Rubin Observatory in 2025, we may either finally find Planet Nine within the next few years — or rule out the idea for good, experts told Live Science.