# Stars, worlds and competing clocks

*The sky above a civilisation*

The physical registers, calendars and astronomical limits behind life in three systems of the rim.

## Three systems, several kinds of home

The places in this atlas occupy three stellar systems within the galactic outer rim. Serev contains Caelune, Damar and the gas giant Ossar, whose inhabited moon is Nereth. Tarsenne belongs to Aunel. Pelaset belongs to Vannor. These are selected inhabited systems, not the complete contents of an imperial territory or a strip along a literal wall at the edge of space.

The common chart gives positions relative to Serev for identifying routes. Its lines record carriage connections, not straight tunnels which a vessel may enter anywhere. Ordinary movement within a system remains subject to acceleration, fuel, orbital position and traffic control. A passage between stars uses a different regime of travel; the departures available to a passenger are narrower than the theoretical capabilities of the ship.

## The stellar register

Observatory exchanges use the old standard solar mass and luminosity as comparison units. An astronomical unit, abbreviated AU, is about 149.6 million kilometres. Values in the register are rounded reference quantities. A precision instrument, a current ephemeris and a competent navigator are still required aboard a vessel; this is not a flight manual.

Serev is a stable, near-solar primary with a mature planetary system. Aunel is slightly less massive and less luminous, with activity that interrupts poorly shielded receivers during some seasons. Vannor is a cooler orange-white star. Its settled world is closer to the primary than Caelune is to Serev, so a redder sky does not by itself mean a colder harbour.

| Primary | Mass / luminosity in standard solar units | Selected inhabited bodies | Observational concern |
| --- | --- | --- | --- |
| Serev | 1.02 / 1.06 | Caelune; Damar; Nereth around Ossar | Conjunctions restrict direct sight lines; crowded inner traffic |
| Aunel | 0.94 / 0.88 | Tarsenne | Receiver damage and survey gaps during active periods |
| Vannor | 0.88 / 0.62 | Pelaset | Cloud cover makes ground optical work intermittent |

## The planetary register

A standard day has twenty-four standard hours. Local rotation is a different quantity. The year column gives an orbit around the star, except that Nereth also has the much shorter revolution around Ossar shown separately. Surface gravity is expressed relative to the old standard, approximately 9.81 metres per second squared.

World averages do not describe the air in a foundry ward, the temperature of a polar plateau or the safety of an enclosed room. Nor do they give a new arrival permission to remove a mask. Port health stations measure the conditions at the port.

| World | Diameter / gravity | Rotation | Orbit / stellar year | Water and habitation |
| --- | --- | --- | --- | --- |
| Caelune | 12,900 km / 1.01 g | 25 standard hours | 1.04 AU / 383.6 standard days | About 64% ocean; open-air settlement widespread |
| Damar | 11,980 km / 0.93 g | 23 standard hours | 1.22 AU / 487.3 standard days | About 43% ocean; cold uplands and temperate basins |
| Tarsenne | 12,560 km / 0.96 g | 26 standard hours | 1.023 AU / 390 standard days | About 69% ocean; highly varied regional climates |
| Pelaset | 11,760 km / 0.89 g | 28 standard hours | 0.84 AU / 299.8 standard days | About 72% ocean; settled coasts and storm islands |
| Nereth | 6,760 km / 0.58 g | 6.52 standard days, locked to Ossar | Ossar at 5.8 AU / about 13.8 standard years | Cold exterior; heated, pressure-controlled settlements |

## Moons, tides and eclipses

Orris is Tarsenne’s large visible moon. Coastal pilots keep local tide tables because the shape and depth of an inlet matter alongside the sky. An eclipse does not cancel a tide or make the current safe. Caelune’s two small moons, Isren and Dath, supply familiar calendar imagery but an unreliable substitute for a harbour notice. Pelaset’s broad tidal flats expose and cover useful routes within a single working day.

Nereth keeps one face towards Ossar. Its orbit lies roughly 880,000 kilometres from the giant’s centre; the resulting 6.52-day cycle produces long changes in the exterior sky. Ossar has approximately 0.67 standard Jovian masses. Service settlements use shift lighting and enclosed agriculture rather than asking vegetables to respect the convenience of a gas giant. Eclipses, radiation forecasts and thermal maintenance belong on the same public board.

## Civil time and the argument over a day

Compact Reckoning is the Orinthian civil chronology, counted from the Lower Estuary Compact. CR 412 is the current reference year. Compact dates used in contracts follow standard hours and an administratively maintained civil calendar; they are not a claim that every imperial world has the same orbital year. Local festival and agricultural calendars continue alongside it.

On Tarsenne, Survey Reckoning 683 corresponds to the opening reference period. Its twelve thirty-day months count local days of twenty-six standard hours. A survey year therefore contains 9,360 standard hours, or 390 standard days. The correspondence with CR 412 identifies the present epoch; subtracting a fixed number from every historical date is incorrect. Older documents must be matched through recorded observations and dated exchanges.

Work contracts specify whether a day means a local rotation, a standard twenty-four hours or a rostered shift. The charitable interpretation of an unspecified day usually belongs to whoever wrote the contract. Nereth’s dockers have a separate term, an air day, for the period purchased by a visitor’s life-support charge. It can expire in the middle of an excellent evening.

## What a chart can honestly show

A Mercator chart preserves local angles while expanding high-latitude areas. Tarsenne’s world chart ends at eighty degrees north and south; the poles are not finite horizontal streets at the top and bottom. Regional and street plans in this atlas are schematic unless a geographical projection is explicitly named. Their north arrows and numbered directories organise relationships; they do not certify a cadastral boundary.

Astronomical distance, political reach and access are different measures. A nearby station can refuse docking. A distant assembly can honour a charter. A ship can carry a message across an otherwise isolated route and leave the recipient without the means to answer it. The distinction occupies a large part of imperial history.

## Explore the Atlas

- [Serev · stellar system](../atlas.html#map=serev-space)
- [Aunel · stellar system](../atlas.html#map=aunel-space)
- [Vannor · stellar system](../atlas.html#map=vannor-space)

## Related entries

- [The Serev system](serev-system.md)
- [Caelune](caelune.md)
- [Damar](damar.md)
- [The Kingdom of Nereth](nereth.md)
- [Tarsenne: planetary almanac](tarsenne-survey.md)
- [Pelaset](pelaset.md)