Eridanus II

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Eridanus II


Eridanus system



Orbital position:

Second planet


One; Ehilend[1][2][3]



1.01 G


1 (N2, O2)

Surface temperature:

-18°C to 38°C (0.4°F to 100.4°F)





510,000 (Post-war) [2]





Eridanus II is a human Outer Colony planet in the Eridanus system. The planet was mostly rural, devoid of pollution or crowding, and had climate-controlled weather.[5] It was famous for its beautiful landscapes and higher learning centers.[2] It was the location of the cities of Luxor and Elysium City, where John-117 grew up until he was abducted and sent into the SPARTAN-II program in 2517. Emile-A239 was from Luxor, born there in 2523.[6]




Known residents[edit]


Rise of humanity[edit]


The secessionist rebels in the system staged a localized rebellion against the UNSC in 2494. The UNSC struck back two years later in Operation: CHARLEMAGNE and forced the rebels out at the cost of four destroyers.[7] A large number of rebels survived, however, and under the command of the UNSC turncoat Colonel Robert Watts, overthrew the civilian government of the system in 2513. Watts was presumed killed in the UNSC's counterattack, Operation: TREBUCHET, but in fact he escaped to Eridanus Secundus in the system's asteroid belt with the rest of the rebels.

In 2517, Dr. Catherine Halsey and Lieutenant Jacob Keyes visited the planet during the former's mission to observe the SPARTAN-II candidates. Halsey met John-117 at a playground in Elysium City's Education Facility 119, where she determined his admission into the program with the flip of an antique coin.[8]

As part of Operation: TREBUCHET in 2524, Colonial Military Authority Marines attempted to raid an Insurrectionist base on Teribus Island. Sympathizers in the unit tipped the Insurrectionists off, and by the time the dropship arrived it had been abandoned. Later, a nightclub in Elysium City was targeted by Insurrectionist bombers because it was a favorite CMA area for off-duty personnel, killing dozens of civilians and a CMA pilot, Allison Stark and putting a CMA Marine, Eric Santiago, into a coma. Gage Yevgenny and Felicia Sanderson were injured, but survived the attack.[9] Around this time, refugees from Eridanus II ended up in Pirth City on Arcadia and New Jerusalem.[10]

It remained a place of much hostility against the UNSC, and many pirates and rebels continued to operate across the system, with the asteroid belt as their main base of operations. John-117 returned to the system in 2525 with the other Spartan-IIs aboard the destroyer UNSC Pioneer for their first mission to capture the rebel leader, Colonel Robert Watts. The Spartan team boarded the cargo freighter Laden and traveled to the rebel asteroid base Eridanus Secundus, where they successfully captured the Colonel and escaped.

At an unknown time, a skirmish between UNSC and Insurrectionist forces during Operation: ROCK HOUSE took place.[11]

Human-Covenant war[edit]

Main article: Human-Covenant war

At some point during the Human-Covenant war, Operation: BLUE MOON took place on the planet.[12] Eridanus II was glassed by the Covenant in 2530 and the UNSC abandoned the planet.[13]


By 2557, the UNSC had reclaimed and resettled the planet, as Nova Austin Station on the planet Cascade offered flights to Eridanus II that year.[14]

Government and society[edit]

The governing of Eridanus II was under the auspices of the Eridanus Government, an ally of the Unified Earth Government (UEG).[7] Boxing was outlawed on the planet.[15]


Kids on Eridanus II, at some schools, can play gravball.[8]

Non-canon and dubious canon appearances[edit]

Silver Timeline[edit]

HTV-SilverTeam logo.png
This article contains information about the Silver Timeline, and is not a part of the established Halo canon.

Originally uninhabited, Eridanus II was settled as a part of the Reach for Life project. The Reach for Life installation on Eridanus II was one of only six to survive its pilot stage, becoming a fertile forest built into an otherwise hostile planet. It was where John-117 was born and lived for the first several years of his life, at one point discovering a Forerunner keystone in a cavern near his home. His parents were the leaders of the Eridanus II colony.[16][17]

However, the program was abruptly terminated when an unauthorized transport brought a plague with no cure to Eridanus II. The plague spread quickly and killed off most of the population with the survivors being relocated to Ehilend. In accordance withe Emergence Contact Protocol Upsilon, the planet was subsequently sealed off to contain the virus. The Reach for Life project's operational files were lost following this.[16]

In 2552, after touching the Madrigal keystone, some of John's blocked childhood memories from his life on Eridanus II were unlocked.[18][19][16] With the help of Cortana and the FLEETCOM Central Database, John eventually identified Eridanus II as the planet from his memories after recalling Eridanus II's visible ice rings which greatly narrowed his search parameters. Cortana revealed what little information she could find about the disaster on Eridanus II, but the Reach for Life project's operational files had been lost when it was abruptly terminated following the fall of the colony. John decided to return to Eridanus II himself to find the second keystone with Dr. Catherine Halsey accompanying him.[16]

John, Halsey and Adun Saly visited the ruins of the Reach for Life installation and John's childhood home where John uncovered his drawings of the keystone and its location. At John's request, Cortana digitally recreated his ruined house which triggered more of John's memories of finding the keystone in a cavern outside of the installation during a family picnic. It also caused John to remember meeting Halsey on Eridanus II before their first supposed meeting at an orphanage on Ehilend. John was then able to lead Halsey to the cavern where the two found the keystone.[17]

Led by Halsey, the UNSC set up a camp on the planet as they attempted to recover the keystone from the caves. Although Saly succeeded in freeing the keystone from the crystal, it sent out an energy pulse that alerted Makee and the Covenant to its location. During his time on Eridanus II, John became more and more suspicious of his "adoption" with Cortana warning him that all of the records about the plague had been lost and there were no records on the Spartan program. Touching the keystone once again, John recalled that he had been kidnapped by Halsey and the UNSC who had replaced him with a flash clone.[20]

The Covenant subsequently attacked Eridanus II for the keystone, destroying the UNSC Pioneer in orbit. During the battle that followed, Atriox successfully stole the keystone and Makee was deployed from a Ket-pattern battlecruiser in an effort to infiltrate the UNSC and get the Madrigal keystone.[20]


Eridanus (or Eridanos) is a river in Greek mythology, associated by Herodotus with the Po River.


List of appearances[edit]


  1. ^ Halo 3: Bestiarum
  2. ^ a b c Halo: Warfleet, page 22
  3. ^ Memory Agent, timestamp Chapter 4: Unsavory Means
  4. ^ Halo Encyclopedia (2022 edition), page 50
  5. ^ Halo: The Fall of Reach, page 22
  6. ^, Emile's profile page: (Quote)
  7. ^ a b Halo Encyclopedia (2009 edition), p. 44
  8. ^ a b Halo: The Fall of Reach, page 21-25 (2001)
  9. ^ Halo: Evolutions - Essential Tales of the Halo Universe, "Dirt"
  10. ^ Hunt the Truth
  11. ^ Halo 5: Guardians Limited Edition, Dossier files - Frederic-104
  12. ^ Halo 5: Guardians Limited Edition, Dossier files - Linda-058
  13. ^ Halo: First Strike, page 240
  14. ^ Halo 4, multiplayer map Skyline
  15. ^ Hunt the Truth, Episode 03: CRITICAL CONDITION
  16. ^ a b c d Halo: The Television Series, episode Emergence
  17. ^ a b Halo: The Television Series, episode Homecoming
  18. ^ Halo: The Television Series, episode Contact
  19. ^ Halo: The Television Series, episode Unbound
  20. ^ a b Halo: The Television Series, episode Reckoning