In a bold and ambitious venture, renowned astronomer Mike Brown, affiliated with the California Institute of Technology (Caltech), firmly believes that a massive, yet undiscovered planet lurks in the distant reaches of our solar system, beyond the orbit of Neptune. He describes this elusive giant as the fifth largest planet in our solar system, waiting patiently to be found. For nearly a decade, Brown and a dedicated team of researchers have been working tirelessly to gather evidence supporting the existence of this so-called 'Planet Nine.'

Despite their efforts, the only tangible clues regarding this mysterious planet have emerged from peculiar anomalies observed in the orbits of several small, Pluto-like celestial bodies. These irregularities suggest that a significant gravitational force is at play, potentially indicating the presence of a large planet exerting its influence on these distant objects. However, the search has proven challenging, as Planet Nine remains unseen, obscured by vast distances and the inherent faintness of such a distant object. The area of the sky that researchers need to explore is enormous, further complicating their quest.

Fortunately, a glimmer of hope has emerged with the anticipated launch of a powerful astronomical facility perched atop a mountaintop in Chile. The NSF-DOE Vera C. Rubin Observatory, a collaborative project between the National Science Foundation and the Department of Energy, has been under construction for several years. Excitement is building as workers prepare to commence the commissioning and fine-tuning of the observatorys advanced instruments later this month.

Brown expresses his enthusiasm, stating, 'I couldn't have asked for a better telescope to hunt my celestial quarry.' He elaborates, 'If you were to hand me a big wad of cash and say, "Go build a telescope to either find this Planet Nine or locate the best evidence possible for it," I would have likely constructed the Vera Rubin Observatory. It is perfectly suited for making the next step in this search.'

Bob Blum, the director of operations at the Rubin Observatory, elaborates on the facility's capabilities, explaining that it will survey nearly the entire southern sky every night, capturing images with the largest digital camera currently in existence. 'The telescope is quite large, allowing it to observe exceptionally faint objects,' Blum notes with optimism.

To enhance its discovery potential, the observatory is equipped with sophisticated computer systems that will continuously compare new images to previous ones. This innovative approach will enable researchers to detect any changes including the potential movement of Planet Nine across the starry backdrop of the sky. 'If it's there, we should be able to find it quite easily,' Blum asserts confidently.

Scott Sheppard of Carnegie Science, who was among the first to propose that a significant planet could be influencing the orbits of smaller solar system bodies, shares Blums enthusiasm. He states, 'Vera Rubin is our best bet to find it in the next few years, probably. It will likely turn over more rocks than anyone has turned over before.' Sheppard estimates that if Planet Nine is real, the observatory has about a 70 to 80 percent chance of discovering it, although he acknowledges the uncertainties involved. 'We don't know the size, reflectivity, or distance of the planet,' Sheppard explains. These factors will significantly impact how bright Planet Nine appears to the observatory.

He cautions that if the planet is relatively small, dark, and located far away, it may remain undetected by the Vera Rubin Observatory, as it would be too faint to observe. However, even in the absence of direct visual contact with Planet Nine, the observatory may still uncover smaller celestial bodies, whose orbits could provide additional evidence supporting the existence of this giant planet. Sheppard emphasizes that until now, astronomers have not identified enough distant minor planets with orbits that can be studied in relation to the gravitational influence of Planet Nine, thus keeping the question of its existence open. 'The statistics simply aren't there to definitively say yes or no,' he concludes.

Brown, however, remains 'extraordinarily confident' in the existence of Planet Nine. Over the years, he has made a concerted effort to maintain a healthy skepticism, but he ultimately became convinced by an obscure gravitational effect that he and his colleagues reported about a year ago. 'If you were to talk to 20 different astronomers, you'd likely get 20 different opinions on how confident they are,' Brown admits. 'But I just don't see a way that the solar system can exist as we know it without there being a Planet Nine.'

As 2023 unfolds, Brown anticipates that the Rubin Observatory will begin to build a comprehensive baseline of the sky, and by years end, it is expected to start detecting changes and releasing relevant data to the astronomy community. 'At that point, we can get serious about trying to find Planet Nine,' he states. Even in the absence of a new planet's direct sighting, Brown believes that the wealth of data gathered by the Rubin Observatory will clarify whether the orbital patterns they have observed thus far hold up under scrutiny. 'I think what Vera Rubin will definitively do is tell us whether we're crazy or not,' he concludes, emphasizing the importance of this upcoming endeavor in the quest to uncover one of the solar systems greatest mysteries.