Parsec

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A Parsec is a unit of length used to measure the distance between stars.

• It is an astrographic scale measurement.
• It is a standard Imperial metric.

Description (Specifications)

The name parsec stands for "parallax of one second of arc", and allows calculating distances to nearby stars using simple observation and trigonometric parallax (apparent motion of an object due to change of position of the observer). It is one of the oldest Terran methods for measuring the distances to stars.

• A parsec is based on a baseline of 1 Astronomical Unit.
• The standard imperial abbreviation is pc.

Image Repository

Term Usage Example

The Imperial world of Regina lies approximately one parsec from the non-aligned Ruie system.

The "Imperial" Parsec

There are actually several different standard parsec values in use within the Imperium for both politico-historical as well as scientific reasons. The general abandonment of the Old Terran Standard was encouraged following the Solomani Rim War to avoid the use of specifically Terranocentric metrics.

 » The Imperial Standard Metric Parsec

Modern Imperial usage defines the AU to be exactly 150 million Imperial standard kilometers, which by extension yields a distance calculation of exactly 500 ls. Given the closeness of the calculated historic value of the old Terran parsec at slightly more than 200,000 AUs, the Imperial Science Union and Imperial Bureau of Standards have defined the Imperial Standard Metric Parsec to be exactly 200,000 AUs. This yields a value of ~ 3.171 light-years.

 » The Imperial Standard Angular Parsec ("Radial Parsec")

An alternative scientific definition of the parsec in the Imperium that is sometimes of greater practical utility for usage in jump theory and technical calculatons bases the parsec on the value of the fundamental constant pi (π) times light-years, equal to 3.142 light-years. This is equivalent to a distance of 198,172 Imperial Standard Astronomical Units. It is known as an Imperial Standard Angular Parsec, or alternatively as a "Radial Parsec".

By coincidence this distance is very close to the maximum distance a Jump-1 drive can jump. Because of this, 'parsec' has become the standard word used for this distance within the Imperium and is officially the Imperial Parsec.

History & Background (Dossier)

Equivalent Metrics

The parsec has been defined differently by different peoples over the History of Charted Space. Other cultures have different values for a parsec:

The "Solomani" (Terran) Parsec

The Solomani define one parsec to be the distance from Terra to a star that has a parallax of 1 arcsecond, and equals 3.261 light-years or 206,265 Astronomical Units.

The "Vilani" Parsec ("Deshi")

The "Deshi" is a Vilani equivalent to the parsec, and is equal to approximately 2.17 light-years.

Other "Parsecs"

Other races, using the orbital distance of their home world and different definitions of an arc second would derive different values for a parsec, but these wouldn't be Imperial parsecs.

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Library Data Referral Tree

Please refer to the following AAB Library Data for more information:
Metrics & Terminology:

• Speed of Travel

• NAFAL (STL) - (Not As Fast As Light) / (Slower Than Light)
• Light Speed (c)
• FTL - (Faster Than Light) - "Superluminal"

• Astronomical Unit (AU)

» Imperial Standard Astronomical Unit

• Light-second (ls)
• Light-minute (lm)
• Light-hour (lh)
• Light-day (ld)
• Light-week (lw)
• Light-year (ly)
• Parsec (pc)

» Solomani Parsec

» Vilani Parsec ("Deshi")

» Imperial Standard Parsec

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References & Contributors (Sources)

This article has metadata.

This page uses content from Wikipedia. The original article was at Parsec. The list of authors can be seen in the page history. The text of Wikipedia is available under the Commons Attribution-ShareAlike 3.0 Unported License.

This list of sources was used by the Traveller Wiki Editorial Team and individual contributors to compose this article. Copyrighted material is used under license from Mongoose Publishing or by permission of the author. The page history lists all of the contributions.

• Marc Miller. T5 Core Rules (Far Future Enterprises, 2013), 615.
• Traveller Wiki Editorial Team
• Contributor: WHULorigan
• Author & Contributor: Lord (Marquis) and Master Scout Emeritus Adie Alegoric Stewart of the IISS
• Author & Contributor: Lord (Marquis) and Master of Sophontology Maksim-Smelchak of the Ministry of Science