The Geometra System: Fragments of the Past

Overview

Deep in the loose, intermediate-age Eruca Cluster is a grand, wide system of eleven strange worlds. The billion year-old Geometra System and its birth cluster drift serenely through the outer reaches of the Comatula ionization shocks as the cluster slowly fragments from the gravity of the surrounding gas clouds. Though Hexastylus and its entourage remain bound, continued mass loss at the current rate will see them break rank and drift off into the void in less than 20 million years.

Geometra has no native cellular life, as the system is far too young, but the water oceans of the two moons Geometra and Synchlora both host a population of sub-cellular replicators like the kind thought to give rise to all proper lifeforms.

Geometra lies in ostensibly unclaimed territory over 100 light-years from even the closest of the ubiquitous comet-riding station-states. Nevertheless, the system has been highly developed by a semi-independent academic institution hailing from Horizon staffed by a wide variety of sapient species dominated by the echinoderm-like Chrysostraca (a native Horizonian lineage). It is the site of several record-keeping centers and also their secure applicational biological collections department, which houses tens of billions of medicinally, industrially, and commercially important species from across the Local Volume.

The First and Only Sun: Hexastylus, the Siliceous Radiance

Hexastylus itself is a relatively typical blue-white A7 star, with 1.7 times the mass of the Sun and 13 times its luminosity. At a billion years of age it is around 60% of the way through its lifetime, though the remaining 640 million years is not much in comparison to smaller stars. There is no notable variability or unusual behavior, though it does rotate unusually slowly. It is a chemically peculiar Ap star as are many other slowly-rotating A and B stars, but in its case this chemical peculiarity is mostly artificial as the resident spacefaring civilization dumps their garbage into its atmosphere.

Hexastylus has a relatively heterogenous and reasonably spaced-out planetary system resembling our own Solar System with the addition of a few more planets, though each planet is comparatively warmer than its Solar-System counterpart. The presence of several solid ice worlds suggests that the development of the system may have been arrested prematurely. The planets are joined by several narrow bands of asteroids remaining from their formation, as well as an outer disk of cold planetesimals stretching for upwards of 5000 AU, far in excess of our own Solar System’s Kuiper Belt.

The Thecostracan Series

False Serenity

Do not be fooled by the inviting appearance of hazy Colossendeis, for this super-Neptune’s cerulean tones are the product of a hellish atmosphere choked with toxic chlorocarbon smog.

The Brazen Bull

Hateful Dendrogaster glows with strange colors under the searing light of Hexastylus, the ruby luminescence of its ionic oceans drowned out by the brilliant sun.

Meloid Vesicant Contaminations

The scarred, pitted surface of pan-seared sub-Earth Laura resembles a bad case of contact dermatitis more than a planetary terrain as the sheer torrid heat deforms and partially melts its crust.

Non-Thermal Emission

The salt-based seas of Sacculina are wholly contiguous with its barely-covered mantle as temperatures just rise and rise as one drills deeper. Beneath the crushing atmosphere, these seas glow crimson in the night.

The Thecostracan Series is the innermost grouping of Hexastylus’s planets. With the exception of the inflated super-Neptune Colossendeis, the series is relatively homogenous, with three resonant terrestrial worlds of approximately equal size. The volatile-rich compositions of all four planets and the resonance of their orbits suggests they migrated in from the outer system, but their small sizes indicate that they could not be from much further than where Endeis is now. The closeness of their orbits sentences all four to a fiery death by engulfment 700-odd million years from now, but they still have plenty of life left in them for now.

Members of the Thecostracan Series

Fly by a bloated, ever-youthful super-Neptune. This hot, gaseous world and its eight round moons scoff in the face of such mortal concepts as age, resisting tidal lock and geologic evolution in spite of the weight of their billion-year lives.
Colossendeis and kin care not for the sensibilities of others.
Witness a world gone soft, grotesquely deformed from its once-clement state and rendered a mockery of its own life-giving past. The ghosts of evaporated oceans have risen as seas of burning liquid salts while clouds of acid and choking chlorine haze replace erstwhile seaside fog.
Such raw hells as hateful Dendrogaster are hard to come by.
Drown in the semi-molten heart of a lost sea. This Earth-sized world’s lost oceans remain as a soupy, pressurized blanket of heavy supercritical fluids much akin to the supercritical seas that cover our Venus, though far more extreme. With the weight of a thousand atmospheres bearing down, its fragile crust is about ready to pop.
Laura shudders as titanic forces rage in its depths.
Observe a world cast in ruin, so far removed that nothing remains of what it once was. The saline seas of this world have transitioned into a global ocean of ionic minerals kept red-hot under a choking, foggy atmosphere and golden, shimmering hazes.
Sacculina forgets its origins even as their remains scar its face.

The Pycnogonid Series

Gossamer Rings

Sericosura glows brightly in the transmitted light of brilliant Hexastylus. Though not every world is physically spectacular, even the demure and humble can show their beauty if given the chance.

Xyloplax Medusiformis

The outer rings of Nymphon reveal themselves in a total solar eclipse, cut through by the razor edge of its shadow. These features owe their existence to a remarkably stable moon system pelted by abundant asteroids.

Parasites and Predators

The gibbous arc of Decolopoda sets over the limb of its moon Macrocheira like some strange, luminous parody of our own Luna.

Recursion in Spades

The rings of Geometra shine bright over its night-shaded atmospheric edge as its grand parent flaunts its own cosmic jewelry in the starless night sky.

The Pycnogonid Series is an intermediary sector containing a set of four gaseous planets ranging from just a few Earth masses to several times the mass of Jupiter. All of the planets in this region experienced a comparatively mild degree of planetary migration, forming around the primordial ice line and migrating slightly inwards to a region encompassing the inner edge of the habitable zone. All four host roughly habitable conditions in their outer atmospheres and the more massive Jovians sustain oceanic moons, but the fast evolution of their host will likely prevent the rise of even simple lifeforms.

Members of the Pycnogonid Series

Glance by a demure, humble world. This low-mass Neptunian world is suprisingly dry, dominated by nitrogen and ammonia gases rather than the typical water. Silicate and carbonaceous dust is abundant in the high haze layers of its atmosphere, building up static that discharges as truly enormous nighttime lightning storms.
Sericosura rages beneath a calm exterior.
Journey to a world cast in sea-foam blue; a living testament to a history so many of its fellows have long since forgotten. Unlike the arid skies of Sericosura, this mini-Neptune’s bulk is almost entirely water in its various forms. In a better world, this giant might develop a thriving ecology like Fortuna’s Catostylus, but alas Hexastylus will not live nearly long enough to allow that.
Witness an ephemeral mirage of never-realized possibilities.
Travel to a world lashed by grand design. This sub-jovian giant’s atmosphere rages with unstable, massive storm systems as its interior churns with great convection currents while its large moons bake under acidic greenhouse atmospheres that pelt them with endless torrential rain.
Decolopoda lashes out from its gravitational prison, hurting none but itself.
Peer into a Jovian world condemned to a brief existence. This giant hosts an abundant array of companion moons from tiny airless rock balls to full-blown oceanic terrae, but the short life of its sun will cut this world down even as life struggles to emerge.
Endeis understands not that its efforts will be in vain.

The Multicrustacean Series

Plankton in the Sea of Stars

Super-aquaria Sapphirina does its best to emulate its biological namesake as it crosses the sea of cerulean glitter that is the Comatula Core. The cluster’s might is undeniable even from hundreds of light-years away.

Serenity in the Sea

An icy, tholin-caked hillside provides an excellent view of great Anoplodactylus. Cleared of haze by the furious UV rays of Hexastylus, Phoxiphilyra is blessed with clear skies unlike so many other Titanian moons at the cost of a vastly shortened life.

Peerless in the Crowd

Calanus stands alone above a peppering of Eruca Cluster stars; other stories and other worlds buried in the distant abyss. One could spend a million lifetimes here alone, but for now this icy world is all that will be.

The outermost reaches of the Geometra System comprise the Multicrustacean Series; a vast toroidal region over 7 times as large as the whole rest of the system combined. The planets here are cold, frozen away from the now-dim light of Hexastylus and covered in cryogenic liquids and solid volatiles. All are somewhat ‘premature’, having grown to super-Earth sizes but in all cases failed to assemble the voluminous gas envelopes their inner neighbors have been able to put together. Perhaps they were late to form, or the protoplanetary disk this far out was simply too diffuse to sustain further growth.

Members of the Multicrustacean Series

Investigate an ethereal beauty created in failure. Even more massive than the mini-Neptune Nymphon, this huge aquaria stayed out in the distal reaches where its surface froze to impenetrable ice. With hazy rings and an entourage of moons of all sizes, it is no way inferior to its giant cousins.
Sapphirina shines with gleaming iridescence.
Tour a giant cloaked in chromatic tones. This dense ice giant consists of a thin veneer of hydrogen surrounding a massive icy core not altogether unlike Sapphirina or Calanus superheated to great temperatures. Exotic chemical reactions in the convection currents of its mantle produce jets and streams of odd gases that color this world with candied stripes.
Anoplodactylus finds not its strange appearance objectionable.
Drift to a frozen remnant on the edge of a precipice. This massive ice world cloaks its scarred, carbonaceous surface beneath a thin atmosphere of nitrogen and cryogenic noble gases, having missed out on the hydrogen once abundant in the protoplanetary disk.
Calanus drifts, alone and content, through the endless dark.