Magnus
Currently unofficial lore, and in progress.
 Enhanced color image of Magnus taken by probe fly-by | |
| Orbital characteristics | |
|---|---|
| 0.47 AU (70,311,000 km) | |
| Eccentricity | 0 |
| 120.3 days (2,890 h) | |
Average orbital speed | 53.61 km/s |
| Inclination | 0.0037° |
| Star | Solakku |
| Physical characteristics | |
| 0.49 R🜨 | |
| Mass | 0.075 ME |
| 4.356 km/s | |
| Tidally locked | |
| Albedo | 0.108 |
Magnus (natively Tivaleh, lit. "soft glow") is the first and smallest rocky planet of Solakku and holds onto no atmosphere. Its surface features relatively few craters as it is very geologically active, which has the effect of constantly smoothing over the surface. The exception to this are the few large impact craters that have managed to flood with molten rock and are a prominent visual feature of Magnus.
Magnus possesses no moons, most likely due to its hill sphere being too small to capture any other bodies.
Physical characteristics
Magnus is the innermost and also smallest terrestrial planet of the Solakku system, consisting of approximately 60% metallic and 40% silicate material. It appears to have a crust varying in density between the night and day sides, which is partially molten on the latter side of the planet, sitting atop a solid mantle encasing a core consisting of solid and liquid layers. Exact compositions or sizes of these layers are difficult to determine due to the hostility of Magnus’ surface.
Surface geology
Near side
Magnus is tidally locked to Solakku, with the day side receiving an average of 97.7kW/m² of solar flux, heating it to up to 1200K, the point of minerals with lower melting points softening or melting entirely. The molten mineral naturally flows to fill depressions in the terrain, most prominently impact craters, creating a distinctive appearance of liquid mineral filled lakes and oceans, colloquially referred to as "lava oceans". This is technically a misnomer as the liquid stems from melting by solar radiation, rather than volcanic activity, which does occur on Magnus.
Minerals with a higher melting point still soften under the intense heat, making the surface of Magnus relatively smooth on the Solakku-facing side, as any steep terrain features would shrink or collapse under their own weight. This process gradually erases all impact craters as well, with even smaller craters smoothing over in just a few years.
Due to this only partially-solid state of the surface, it begins to behave more like a sponge due to small bubbles and pores forming in the rock. These create capillary forces that may draw in molten mineral to fill the space, meaning that the amount of liquid on Magnus is far greater than what can be seen from space, but also that the ground near the shores of Magnus can take on mud-like characteristics, but with superheated minerals rather than water.
Far side
Magnus’ far side is in perpetual darkness, allowing it to cool and solidify. Larger structures such as mountains can theoretically exist here, but very few examples of such terrain features can be found, with most having been created by impactors, as their craters are not erased by heat on this side. Further surface analysis also showed large basins of solid igneous rock surrounded by cool but porous metamorphic rock, which suggests that the surface on this side was also once subjected to intense heat and melted in the same manner as the Solakku-facing side.
This appears impossible at first glance due to the tidally-locked nature of Magnus, however, a particularly large basin surrounded by displaced material found on the northern hemisphere on this side was determined to be the result of a particularly large impact. It is thus hypothesized that this impact imparted enough energy onto Magnus laterally to slightly impact its angular velocity. Tidal forces would have synchronized the planet’s rotation period to its orbital period again within a few hundred years, re-establishing the tidal lock, but would’ve induced a small drift of the the planet’s orientation relative to Solakku by at least 180°, flipping the day and night sides.
The impact would have to have been particularly powerful for this, however. Assuming a drift of exactly 180° caused by a perfect impact angle imparting an impulse directly opposite to Magnus’ angular velocity, the impulse energy would have to exceed 2.6×1022 J. But as only a portion of the impact’s energy is released as a kinetic impulse, the total energy of this impact could be as high as 5×1024 J. This is not theoretically impossible as this could be generated by an impactor with a mass of 1.5×1016 kg traveling at 23 km/s. Comets of this mass have been detected, and as Magnus is deep within Solakku’s gravity well, any object in a highly eccentric orbit sharing the planet’s periapse will accelerate to comparable speeds near periapse. There are alternative explanations for Magnus’ shift in orientation, such as chaotic rotation, but the impactor theory has by far the widest support and evidence promoting it.
In any case, the fact that Magnus has flipped at least once in its life makes it near impossible to study its geologic history as any features from earlier points in its existence have been destroyed by intense heat on both sides of the planet. For instance, it is impossible to tell if Magnus ever harbored true volcanic activity, though it is safe to assume it once did, finding evidence of this would require studying its composition deep below the surface (i.e. through sample drilling), which would be both incredibly costly and dangerous and has thus far not been attempted.
Magnetic field
Magnus has a global, though weak magnetic field, the only evidence of liquid layers in its core. At its strongest, it reaches only 57 nT and is aligned with the planet’s spin axis. It is assumed that tidal heating from Magnus’ orbit is what keeps a layer of the core hot enough to remain liquid, allowing it to generate a magnetic field through the dynamo effect. This magnetic field forms a weak magnetosphere as it partially deflects the solar wind, though a large portion of this radiation still reaches the planet’s surface.
Observation
Similarly to Infernum, Magnus can be observed by the naked eye, appearing as a particularly bright star, though not as intensely as Infernum, leading to its name, as its appearance is softer then that of Infernum. It is also easier to observe as its wider orbit takes it further away from Solakku in the sky. It was thus also known to many early cultures all across Avalon.
Telescopic observations showed that Magnus varied in brightness with its position in the sky, leading early astronomers to conclude that it must display phases similarly to Solvis and all of Valaya’s moons. Although attempts were made to map its surface through telescopic observation, its high albedo made this difficult, leading to the presence of molten minerals on its surface not being discovered until the first fly-by by a space probe.