The Astrologian Mage

The Astrologian mage stared at the intractable problem. Hundreds of small globes representing planets, moons and asteroids traversing the solar system hovered on the desk in front of her, rapidly orbiting a blue glowing ball, accelerated one hundred times. The fourth planet completed a rotation around the large origin star every three and one third seconds. That planet, her planet, was surrounded by what appeared an inner circle and an oval around that. following the natural paths of two of its three moons. More importantly, those moons weren’t the problem.
    The third moon was, and part of that problem was not knowing whether Vloed could be called a moon despite the epochs of history that called it such. Grace stood up and paced in front of the model repeating to herself what she knew, at this point, by rote.
    “..and e is zero point nine five. Orbital period nine years exactly, to the second. How can an orbit be that stable?”
    Of course, she knew that was a simplification. It wasn’t entirely stable. As Vloed approached the planet every nine years, the gravitational pull of the planet slowed the moon’s velocity. The pull wasn’t strong by any means, but it was enough to make a difference over time. When it happened, it moved close enough to generate modest heat and distortions of gravity. Twenty seven days during which rain never fell. Where the problem lie was that every completed orbit brought Vloed closer to the dreaded moment it would inevitably slice through the atmosphere and scorch her entire world.
    Two hundred and one years. That’s how long the College of Astrology had to solve this problem. Grace would be dead long before that happened. But coming up with a solution… she would be known as the savior of Issanara, her name spoken with reverence, forever.
    “What’s ‘e’?”
    Grace turned to the young girl holding a tray of food walking toward her desk.
    “Oh Pom, good you’re here. Eccentricity. What’s for lunch today?,” Grace said.
    “Barley Stew, flatbread and custard. What’s eccentricity,” Pom said, blowing into a spoon and wiping it with a towel attached to her apron.
    “Come here and I’ll show you. You see this globe here, hold on one second.” Grace said. She made a couple gestures with her right hand and the balls slowed to near stillness.
    “That’s us, right?” Pom said.
    Grace looked at the girl with a smile, “Yes! And you saw how the two solid rings around it slowed down to reveal themselves as our moons, Kets and Loek. The distance between Kets and Issanara is uniform, so it has an eccentricity, an e, of zero. However, Loek’s outer orbit you can see is closer to our planet on one side compared to the other, which is an e of around zero point one nine.”
    Pom scrunched her nose for a moment. “What about an e of five?” 
    Grace laughed and dipped a piece of bread in her stew.
    “Good question. Any eccentricity one or above would no longer be an orbit, but rather a rogue body.”
    Using her fingers to draw an imaginary orbit around her planet, Pom widened the distance on one side every rotation until she reached the end of her arm span.
    “So, an e of nine fi, no.. zero point nine five, is why we can only see Vloed for a few months every streak?”
    “Yes.. well no, not exactly. We can actually see Vloed for about three years and two months before and after perigee, what we call the the closest approach. But not every hour of the day and only with good lenses. Then, for five years and eight months, it’s beyond the distance we can see it, for now at least.” Grace smiled and ate, letting the girl think.
    Pom moved her gaze from one ball to another, occasionally using her fingers to trace the paths.
    “So if this is Vloed..” Pom paused and Grace nodded her head while chewing, “..that means it goes to the outer edge of our... system?”
    Grace chewed faster bobbing her head back and forth before swallowing, “Yes. And that is not the strangest thing about it.” She took a drink and stood up.
    “In this model, Vloed goes beyond the orbit of Aziter here, our seventh planet, and the rest is all approximation. Based on the angle it’s traveling in its elliptical orbit, there’s a probability that it orbits around another body further out in a figure eight like so before it passes Aziter’s orbit back on approach. But if that were true, that would mean there’s a body further out that has enough velocity and mass to orbit Mother Shine, our origin star, exactly every nine years in a stable orbit itself. That’s the main reason the figure eight theory is discounted. The likelihood of that is so small that you would have a better chance of drawing a full castle in cards on your first turn, every game, for the rest of your life.”
    The girl cocked her head as Grace gestured, “But a full castle requires seven cards and you 're only dealt five to start.”
    Grace grinned, “Exactly, Pom.”