Outer Wilds Wiki

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Outer Wilds Wiki

Brittle Hollow is the third of six planets in the Outer Wilds' solar system. Befitting its name, the planet consists of a brittle, rocky crust, surrounding a hollow interior with a large Black Hole serving as the planet's core. Regular bombardments from the planet's moon cause fragments of the fragile crust to break over the course of the loop, falling into the black hole core.

The planet is home to numerous Nomai structures scattered both on and under the planet's crust, including the enormous Hanging City, the Tower of Quantum Knowledge, the Southern Observatory, a Gravity Cannon, and the Black Hole Forge used by the Nomai to craft the warp cores for the Ash Twin Project.



Brittle Hollow is a highly unstable planet that formed naturally around the black hole at its center. Its dry, rocky surface is fractured and prone to collapse, and in each 22-minute cycle of game time, the player can observe as most of the planet's crust breaks away and falls into the black hole. These pieces then emerge at the White Hole next to the White Hole Station. This collapse is precipitated by the balls of lava ejected from the planet's moon, which rain down steadily and crash into Brittle Hollow's surface.

Traversing the planet's precarious remains is a challenging task, but despite the likelihood that a player will slip and fall into the black hole, the fact that White Hole Station lies very close to the black hole's exit point means that the planet's long falls are less dangerous and more inconvenient.

Escape Pod 1 resides on the surface, its metal tempered by the heat of its descent to the planet. From the escape pod the player can follow a trail of precarious wooden bridges created to span the gaps between rocks, indicating that the enormous drop towards the planet's core existed millennia ago when the Nomai first entered the system.

The planet's two poles are topped with snow, and the north pole has flowing water. This leads to ice formations beneath the surface into which the Hanging City is built.

The rest of the planet's interior is made up of a mixture of blue metallic and red crystalline rock formations. The geometric lattice of these formations exhibit clear fracture points and planes of weakness, which makes it susceptible to the collapse that the player can witness in action during the game.

Hollow's Lantern[]

Brittle Hollow is orbited by the volcanic moon, Hollow's Lantern. The lava level slowly lowers as time goes on. The balls of magma that shoot from the moon crash into the surface of the planet, precipitating the collapse of the planet's crust. The Nomai named Root used the moon's lava to heat-test mineral samples supplied from the Nomai mines on Timber Hearth. These samples were then used to encase the Ash Twin Project.


Northern Glacier[]

The icy northern pole of the planet, which possesses several ruined Nomai structures lying above the Hanging City. The Nomai warp receiver connected to the White Hole Station's warp tower is present here, and nearby Nomai writings discuss the negative time discrepancy between warps.

A larger ruined building possesses two gravity lifts connected to the Hanging City, but the lift down into the city is blocked and non-functional. However, a flowing river runs through the Glacier, at the end of which a hidden hole leads down into the Hanging City. The river flows into this hole, creating a waterfall that leads into the City's Meltwater District.

Hanging City[]

The Hanging City is the biggest Nomai settlement in the Solar system, hanging to the thick ice under the Northern Glacier where the planet's crust was stable enough for a long-term settlement. Having moved from the Old Settlement, the Nomai in Brittle Hollow both survived and thrived.

The City is divided into four districts located on top of each other, all accessible by a tall vertical passageway with gravity panels.

From highest (nearest to the surface) to lowest, the districts are the Black Hole Forge District, the Eye Shrine District, the Meltwater District, and the School District. The vertical passageway is broken near the top, cutting off conventional access to the Black Hole Forge District.

Black Hole Forge[]

The Black Hole Forge is a massive Nomai structure, suspended on rails attached next to the Hanging City. The Forge itself can be moved along these rails from a control room in the Meltwater District, and can be raised up to the highest level of the Hanging City, or lowered down to the black hole at the planet's core, where it is by default.

The Forge can only be accessed when raised to the uppermost level of the Hanging City - the Black Hole Forge District, which is constructed entirely out of gravity panels attached to the underside of the planet's crust, therefore being upside-down. The district contains a warp receiver, connected to Brittle Hollow's corresponding warp tower on Ash Twin.

The Nomai used the Forge to craft the warp cores used throughout the solar system from the black hole itself, as well as the Advanced Warp Core for powering the Ash Twin Project. Writings and a diagram within the forge explain the mechanics of warp alignment, with the towers having an approximate five-degree window with which to align with their corresponding receiver's astral body.

Meltwater District[]

The second lowest level of the Hanging City. It is connected to the Crossroads by two bridges, and houses a control room that raises and lowers the Black Hole Forge. Ruined Nomai buildings contain writings detailing methods of procuring an advanced Warp Core for the Ash Twin Project, and leads to a passage to the surface river on the Northern Glacier. The waterfall caused by the river flowing into the hidden cavern lies adjacent to the District, and acts as the District's namesake.

Eye Shrine District[]

The Eye Shrine District, similar to the identically named district in Ember Twin's Sunless City, houses many derelict Nomai buildings and a small shrine with writing detailing the Nomai's thoughts and knowledge about the Eye of the Universe.

School District[]

The lowest district, made for the Nomai children who lived on Brittle Hollow. Inside are classrooms with writing explaining the Nomai's history stuck in the solar system and the Nomai tradition of 'festivals'. From here, a long gravity crystal path runs along the underside of Brittle Hollow's crust that leads to the Old Settlement on the planet's equator.

Gravity Crystal Workshop[]

A small collection of buildings that lies on Brittle Hollow's surface equator, where the Nomai first designed and constructed Gravity Crystals. Riebeck's first camp can be found here, with directions to their current camp written nearby. Under Riebeck's direction, a gravity crystal passage leading to the underground Crossroads can be found within a building overgrown by a tree. Another nearby workshop building is caked entirely in Ghost Matter.


A mural of Brittle Hollow's locations. From the top clockwise, it depicts the Hanging City, the gravity cannon, the Southern Observatory, and the Tower of Quantum knowledge.

A two-leveled central hub location under Brittle Hollow's surface, that contains Riebeck's camp, a map of the Nomai structures on the planet, and acts as a central node between most of them. The map depicts the important Nomai locations and pathways that exist between them, though centuries of deterioration means some of the pathways have broken down and will continue to do so over the course of the loop.

The Crossroads can be accessed from the surface by the Gravity Crystal Workshop on the planet's equator. The workshop and both levels are connected by gravity crystal paths, with the bottom level also possessing a gravity lift leading up from the black hole, intended to potentially save any who accidentally fall towards the black hole by returning them to the Crossroads.

As depicted in the map mural, the Crossroads connects to the Hanging City, the Gravity Cannon and the Tower of Quantum Knowledge by varying passages, with the latter two also containing pathways to the Southern Observatory. However, the deterioration of Brittle Hollow's crust heavily affects these pathways over the course of the loop.

Two large Nomai bridges lead north to the Hanging City's Meltwater District on the Crossroads' top level. Sections of the bridges will collapse over the course of the loop due to bombardment. A pathway east to the Gravity Cannon is also present, made up of natural crust fragments that must be leapt between to reach the Cannon.

A highway of initially unbroken gravity lifts leads west to the Tower of Quantum Knowledge on the Crossroads' bottom level.

Gravity Cannon[]

A massive Nomai structure on Brittle Hollow's equator, intended to launch Nomai shuttles with gravitational force, accessible from the Crossroads or the surface. The cannon is linked to a shuttle belonging to a Nomai named Solanum, now currently on the Quantum Moon. The shuttle can be recalled using the cannon's controls to read the notes inside written by Solanum, just after landing the shuttle on the Quantum Moon and just before setting foot outside.

From the Gravity Cannon, the Southern Observatory can be reached via a series of gravity lifts and broken platforms of crust. However, the gravity lifts are misaligned due to the planet's deterioration, and care must be taken when transferring between lifts using the jetpack. Note that the Gravity Cannon is likely to fall through the black hole near the end of the loop.

Escape Pod 1[]

The first Nomai Escape Pod, crash-landed at Brittle Hollow's equator. Opening the Pod's emergency hatch reveals a treacherous and fragile pathway of stairs and bridges leading under the crust of the planet to the Old Settlement. The stairs and bridges collapse with enough force, falling into the black hole if one is not careful.

Old Settlement[]

The original Nomai settlement, located on the equator under the crashed Escape Pod 1, where the Nomai inhabiting the pod first made their home on Brittle Hollow, hidden under the surface to shelter from Hollow's Lantern. A pathway of fragile stone stairways and bridges leads to the settlement from the Escape Pod, and also connect the ruined houses and pathways within, collapsing under enough force.

The settlement itself is consisted of scattered Nomai houses and buildings embedded in the underside of Brittle Hollow's crust, with a network of fragile bridges and pathways connecting them. Nomai murals and writings can be found throughout detailing the Nomai's history regarding the Escape Pod's jettisoning from the Vessel, revealing the Vessel's ensnarement in Dark Bramble and the other Pod locations. After a while, the Nomai realized this part of the crust was still too exposed to Hollow's Lantern's bombardment, and they moved north along a gravity crystal path underneath the crust to settle in a safer place, eventually creating the Hanging City.

Tower of Quantum Knowledge[]

The tower shard, above the Tower of Quantum Knowledge

A massive Nomai tower, suspended from a section of Brittle Hollow's crust where the Nomai found a Quantum Shard, the Tower Shard, and contains information crucial to the Quantum Moon pilgrimage. The tower may be found easily from the surface, or the gravity highway from the Crossroads. A heavily ruined gravity highway leads from the Tower to the Southern Observatory, with many sections missing and gravity pathways cut short, necessitating many great and careful leaps to traverse.

While the tower's bottom level can be easily reached via the Crossroads or walking down from the surface, the upper levels are inaccessible by conventional means at the start of each loop, as the gravity panel path leading into the tower is broken and impassable.

However, the planet's ongoing destruction is likely to drop the tower through the black hole partway through the loop, and, once it exits at the White Hole Station, can be freely explored in zero-gravity.

The surface of the Tower contains the Tower Shard and other quantum objects affected by the Shard. The Shard itself has a Nomai writing wall attached to it that also transports with it, providing a mild hint to the rule of quantum entanglement.

The upper levels of the tower contain two scrolls (one congratulating a Nomai named Solanum on reaching the last step before she travels to the Quantum Moon, and one on a shelf that reminds the pilgrim that they're taking part in a tradition of curiosity and exploration by following in the footsteps of everyone before them who sought the Quantum Moon) and a Quantum Moon Locator built into the Tower's interior.

Southern Observatory[]

A domed Nomai observatory on the south pole. The entrance on the surface is broken from the outside, with the only accessible route being beneath the surface. Riebeck's ship and recorded notes of their plan to search the Nomai ruins on the equator for a path underground lie outside the surface entrance.

The Observatory can be accessed from underground via the broken gravity pathways from the Gravity Cannon, requiring care to traverse and move from pathway to pathway without falling.

Within the Observatory is an Eye Signal Locator, built after and more sophisticated than the Locator on the Attlerock. The Locator's modules can be individually activated to show the orbits of each planet in the solar system, including the Eye of the Universe. However, the Locator is also unable to locate the Eye's orbit, erratically creating models of potential orbits instead.

On the same level as the Locator controls are two conversations about the Nomai's ongoing search for the Eye. One covers what they know about the Eye so far and laments their lack of progress finding it. In the other, the Nomai Mallow suggests simply launching a probe into the outermost reaches of the solar system to see if it happens to find the eye. Cassava points out that the odds of randomly firing the probe at the correct trajectory to find the Eye were extremely small, but Conoy points out there's another ongoing project that could take luck out of the equation.

Also contained in the Observatory are two active models of Giant's Deep cyclones, created by a Nomai named Spire to aid the team building the Orbital Probe Cannon. The models depict two varieties of cyclone - the most common spinning clockwise and upwards, and a rare variety that spins anticlockwise, and forces things downwards instead. Next to the entrance is a projection stone of a conversation with the team building the orbital probe cannon on Giant's Deep, who had been using the cyclones to launch parts into orbit only to have one piece unexpectedly driven beneath the ocean's usually-impassable current.

Texts and recordings[]


Notes & Trivia[]

  • If you happen to slip and fall towards the black hole, its possible to slingshot yourself around it using your spacesuit's thrusters. There is a conveniently placed gravity lift extending down to black hole's edge, and lucky or skillful players that can maneuver themselves into its path can spare themselves the trek back from White Hole Station. This gravity lift will helpfully deposit the player at Riebeck's camp, which offers a campfire, oxygen, and a fuel tank.
  • With lots of luck or skill, you can make various jumps below the surface that traverse almost half of the planet.