Epsilon Eridani

The Epsilon Eridani system, located 10.5 light years from Sol, is a notable slipspace crossroads system of the Human Sphere and formerly one the most notable human-inhabited system outside SolCore.

Planetary system
The Epsilon Eridani system is home to four inhabited planets, two asteroid belts, and several gas giants and minor planets. Planets are listed in order of orbital position.

Hadur
A small, metal-rich rocky planet orbiting close to Epsilon Eridani. Hosts a minor mining colony and orbital refineries.

Reach
Initially terraformed and colonized by Hungarian settlers in 2319, the most major industry was titanium mining and refining. Additional waves of colonists displaced the Hungarians and paved the way for Reach to become the UNSC's headquarters.

The smaller of Reach's moons. Originally inhabited only by research stations, but largely given over to refugee housing.
 * Turul

Reach's largest moon, Csodaszarvas has a gaseous atmosphere, as well as a peculiar ring system, which is suspected to have been formed as recently as 100,000 years ago. Its unusual traits make the moon the object of considerable scientific interest.
 * Csodaszarvas

An industrial sector comprised of hundreds of microgravity factories and refineries, the first of which were established by the industrialist Harry Stine.
 * Stine's Archipelago

Tribute
The most prominent civilian colony in the Epsilon Eridani system, and the only one with 'shirtsleeve' weather prior to terraforming. It is smaller than Earth and has a lighter gravity.

Tribute was spared the brunt of the Covenant invasion as the Covenant focused most of their might on Reach. Still, most of the planet's cities and industries were glassed by raiding parties, though a number of smaller settlements survive, and the glassing was not widespread enough to destroy the planet's ecosystem and climate. Post-war, it has become Epsilon Eridani's most notable resettlement project, with hundreds of thousands of refugees flowing in from across the human sphere.

Circumstance
A large ocean world that lies at the edge of Epsilon Eridani's Goldilocks zone, Circumstance's surface is entirely covered in a vast ocean which freezes toward the poles, leaving only a narrow temperate band around the planet's equator. While famous in the modern day for high courts and academies of justice, Circumstance was originally important for the resources and the industry needed to tame the Epsilon Eridani system. Its peculiar orbit keeps it near known slipspace jump points, which made the planet a crossroads of the system and the first step for colonists from Earth. Befitting its nature as a waystation, most of Circumstance's settlements are atop its gravity well in several orbital stations, though the planet also hosts surface cities on floating seasteads, along with various undersea research stations. Home to some native deep-sea life of its own, Circumstance also hosted a notable cetacean transplantation and intelligence research project early on in its history.

Today, Circumstance hosts several aquatic farms created during the Covenant War to feed the rest of the Epsilon Eridani system due to shortages created by the loss of out-system agri-worlds. During the Covenant invasion of the Epsilon Eridani system, Circumstance was attacked by Jiralhanae-led raiding parties, though it never received the attention given to the larger colonies in the system. Still, much of the population either escaped or were killed, and many of the seaborne arcologies were destroyed. After the retake of the Epsilon Eridani system, plans were laid for the recolonization of the planet and the restoration of the more intact seastead cities and orbital habitats. The surface colonies expanded in the post-war era as a dumping ground for refugees from Reach and Tribute, as well as migrants and refugees from elsewhere in the human sphere. A portion of the refugees who did not go on to settle on other worlds now inhabit vast raft-cities built in and around the ruins of the world's seastead arcologies, as the influx of population too fast for the formal rebuilding and expansion of those seasteads to accommodate. Yet more have crowded the orbital communities awaiting for the Phoenix Initiative's resettlement plans to come to fruition.

One of the original stations built to support the colonization of the Epsilon Eridani system. Niven Station is also the largest spin-gravity station ever built in Human territory, having been built with three 770-meter rings and expanded until the Dzhanibekov Effect threatened its stability.
 * Niven Station

Beta Gabriel
A small, uninhabitable ice planet with a subsurface ocean. A smattering of arcologies (including a peculiar domed-off artificial 'wilderness preserve' created by a private corporation as a retreat for the wealthy) brought the planetary population up to a few hundred thousand. Prohibitive cost of development prevented settlement even by desperate evacuees from the outer colonies.

Aegir
A gas giant classically designated Epsilon Eridani b. Orbiting fairly close to the system's inner asteroid belt, Aegir is home to the system's primary helium-3 and hydrogen scooping operations and several lesser colonies on its moons.

The second-largest moon of Aegir, hosting a relatively small surface colony in the form of various subsurface warrens and domes.
 * Tantalus

Epsilon Eridani c
Gas/ice giant.

Epsilon Eridani d
Gas/ice giant.

Early-warning system
The Epsilon Eridani early-warning network was extensive, comprising various automated and manned remote-sensing and reporting satellites with a focus on monitoring likely slipspace entry points and inbound trajectories. In the 2550s, these systems were supplemented with early wavespace communicators connected to the system's nascent slipstream comm buoy network, enabling them to get messages across to Reach much faster than before. Some of the more notable platforms included:


 * RSOs Fermion, Boson, Axino, and Dyon in the inner cometary belt.
 * RSOs Hadron, Baryon, and Meson in the L3, L4, and L5 Lagrange points, respectively, between Aegir and Epsilon Eridani.