Chapter 1: Introduction to Planet 9

How many planets reside in our Solar System? While the answer seems simple—eight recognizable planets: Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, and Neptune—scientists have long speculated about the potential existence of a concealed giant planet lurking in the outer regions. This hidden planet is theorized to exert a gravitational influence that distorts the orbits of asteroids and planetoids beyond Neptune. Despite extensive searches, this elusive object has remained undetected. Recent research, however, may have uncovered evidence of our distant neighbor using data from four decades ago. Could this be the elusive 'Planet 9'?

Before delving into the 1980s data, it's crucial to understand why Planet 9 might exist and the challenges we face in locating it.

Neptune — Photo by NASA on Unsplash

Beyond Neptune lies a region teeming with thousands of asteroid-like bodies known as the Kuiper Belt. These celestial objects, composed mainly of frozen nitrogen, planet fragments, and even captured interstellar materials, exhibit peculiar orbits that cannot be solely attributed to the gravitational pull of Neptune.

These distant objects follow highly elliptical paths, oscillating between distances close to Neptune and as far as tens of billions of miles from the Sun. Their orbits are skewed to one side, suggesting that they should become more evenly distributed over time—unless, of course, there is a massive planet on the opposite side. This hypothetical planet, estimated to be 5 to 10 times the size of Earth, would orbit at a distance of 400 to 800 astronomical units (AU), helping to stabilize the orbital dynamics of the Kuiper Belt.

The notion of Planet 9 is grounded in this hypothesis, but why haven't we visualized it yet? Wouldn't the Hubble Space Telescope have captured it? Given that Hubble can observe galaxies billions of light-years away, one might think it could detect Planet 9.

Even Hubble shouldn't be able to spot Planet 9 — Photo by NASA on Unsplash

The truth is, Planet 9 orbits at such an immense distance that even Neptune, the farthest recognized planet, resides 30 AU away from the Sun. Thus, Planet 9 is estimated to be over ten times further out! This extreme distance results in minimal sunlight reaching it, rendering it incredibly dim in our night sky.

If one were to stand on the surface of Planet 9, the Sun would merely resemble another star, shining slightly brighter than the others. The reflective nature of Kuiper Belt objects, primarily composed of nitrogen ice, is why we can detect them; Planet 9 is likely a rocky body that reflects far less light.

Consequently, even advanced telescopes like Hubble may not be capable of detecting Planet 9 due to its dimness. Despite our repeated scans of the relevant part of the sky yielding no visual evidence, this absence does not negate the possibility of its existence; our current telescopes may simply lack the sensitivity required to detect it.

Some scientists even hypothesize that Planet 9 could be a primordial black hole, perhaps the size of a football—a topic I explored in a previous article.

Chapter 2: The 1980s Discovery Attempt

How then did telescopes manage to observe it in the 1980s?

The key instrument was the Infrared Astronomical Satellite (IRAS). This telescope was to the 80s what Hubble is today, capable of extraordinary observations not possible from the ground. Unlike Hubble, which captures light across various wavelengths, IRAS operated exclusively in the infrared spectrum.

Objects emit infrared radiation when heated, giving IRAS a "heat vision" capability. Its sensitivity allowed it to identify the cold Kuiper Belt objects against the cooler backdrop of space.

However, identifying new Solar System objects with such technology can yield false positives. For example, distant gas clouds or even galaxies may mimic the signature of a Kuiper Belt object or planet, necessitating multiple algorithms to filter out these erroneous signals.

Computers at the time struggled to process the data — Photo by Lorenzo Herrera on Unsplash

In the 1980s, the algorithms and computing power required for this analysis were lacking. As a result, determining the nature of IRAS's findings proved challenging and often required corroboration from other telescopes. While comets, known for their brightness, could be verified through other observations, IRAS's potential detection of Planet 9 could not be confirmed, leaving its signal concealed for decades.

Today, however, we possess advanced machine learning techniques and computing capabilities unimaginable in the 80s. As a result, sifting through the massive IRAS dataset has become a manageable task.

Michael Roman-Robinson from Imperial College London undertook this challenge, searching for any signs of Planet 9. After meticulously filtering the data through various processes, one reading stood out. It was a signal measuring just three pixels across, suggesting a planet with an orbit of 225 AU and a mass 3 to 5 times that of Earth. Could Michael have found Planet 9?

Planet 9 Exists! New Evidence Confirms Its Presence Beyond Neptune - YouTube

This video discusses the recent findings concerning Planet 9 and how they relate to earlier theories about its existence. It provides context for the ongoing debate and investigations surrounding this mysterious planet.

Yet, skepticism remains. The orbits of the Kuiper Belt objects indicate a larger orbit and a heavier planet. Thus, it's plausible that this reading could be a false positive that slipped through the filtering process, as it doesn't align with our expectations of Planet 9.

Michael has proposed conducting further dynamical studies to ascertain whether this potential Planet 9 could still explain the orbits of the Kuiper Belt objects. Additionally, further infrared imaging will be necessary to explore the region of space where this candidate Planet 9 is believed to reside.

These dynamical studies are complex; the gravitational interactions between various orbiting bodies create a chaotic environment. Running simulations that account for these interactions can be time-consuming, even for the most advanced supercomputers. Moreover, the imaging precision required to visualize Planet 9 is immense, necessitating repeated observations with current telescopes, which may be constrained by competing projects.

Especially concerning is the fact that our best infrared telescope, Spitzer, which was sensitive enough to image Planet 9, has been decommissioned. Thus, we must await the capabilities of the James Webb Space Telescope to potentially capture images of Planet 9.

NASA Spitzer IR Space Telescope — WikiCC

If simulations reveal that Michael's proposed Planet 9 could indeed influence the orbits observed in the Kuiper Belt, and if our telescopes can successfully image it, we may finally have definitive proof of Planet 9's existence.

Until then, the evidence remains tantalizing but inconclusive, teasing us with the possibility of a distant world that has eluded our detection for years.

The mysteries of the Universe are astounding. We have witnessed supernovae, captured images of black holes, and discovered ancient galaxies at the far reaches of our observable cosmos. Yet, a massive planet in our own celestial neighborhood has successfully remained hidden from us all this time. What other secrets lie undiscovered in the vastness of space?

Does Planet 9 Exist? - YouTube

This video delves into the ongoing investigation surrounding Planet 9, exploring the evidence for and against its existence while outlining the challenges faced by astronomers.