Resonant Orbit

A Resonant Orbit is a relationship between the orbital periods of celestial objects.

• Orbital resonances may occur between Planets, Moons, or even Asteroids.

Description (Specifications)

An orbital resonance is a relationship in which the orbital period of one world is related to that of another by a simple integer fraction, such as 2:1, 3:2, or 4:3:2. It describes the number of orbits around the star each member world of the resonant sequence completes over the same period of time compared to the others, moving from the innermost world to the outermost world.

This arrangement of worlds is called a resonant chain.

For example, three worlds within a system form a resonant chain and have a 4:3:2 orbital resonance with one another.

• The inner world will complete four orbits in the same amount of time that the middle world takes to complete three orbits and that the outer world takes to complete two orbits.
• If the inner world completes one orbit every 30 days, the middle world completes one orbit every 40 days, and the outer world completes one orbit every 60 days.
• In 120 days, the inner world will complete exactly 4 orbits, the middle world will complete exactly 3 orbits, and the outer world will complete exactly 2 orbits.

Star System Locations

See Orbit, Orbital Zone

History & Background (Dossier)

The longest known chain of resonant orbits to date is the TRAPPIST-1 system, near Terra: the system is centered on a small red star and contains seven rocky worlds with a resonance of 24:15:9:6:4:3:2 with one another.

Many of the planets and moons of the Terra system share orbital resonances. Among the most well known are Io, Europa, and Ganymede, moons of Jupiter with a resonance of 4:2:1 and orbital periods of 42 hours, 85 hours and 172 hours respectively; and Pluto and Neptune, with a resonance of 3:2 and orbital periods of 165 years and 248 years respectively.

Resonances may be relatively short-lived phenomena ("meta-stable"), lasting for a few million years before outside forces (such as the gravitational pull of a gas giant world) change the orbits of the planets within the resonant chain and destroy it. Resonances can be self-correcting and can remain stable over billions of years.

See also

Universal world profile

§ == ( Please refer to the following AAB Library Data for more information: ) == §

• Main world
• Hex Number
• Universal World Profile
  • Starport (Sp)
  • Planetary Size (S)
  • Atmosphere (A)
  • Hydrosphere (H)
  • Population (P)
  • Government (G)
  • Law Level (L)
  • Tech Level (TL)
• Trade classification & Sophont Codes
• Importance Extension (Ix)
• Economic Extension (Ex)
• Cultural Extension (Cx)
• Nobility
• Bases
• Travel Zone
• PBG - Population, Belts, Giants
  • P: Population Multiplier
  • B: Belts
  • G: Gas Giants
• Worlds
• Allegiance Code
• Stellar Data
• COG Sequence
  • C: Climate
  • O: Orbit
  • G: Gravity

References & Contributors (Sources)

This page uses content from Wikipedia. The original article was at resonance Orbital resonance. The list of authors can be seen in the resonance&action=history 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 Far Future Enterprises or by permission of the author. The page history lists all of the contributions.

• Marc Miller. Imperial Encyclopedia (Game Designers Workshop, 1987), TBD.
• Frank Chadwick, Dave Nilsen. Traveller: The New Era (Game Designers Workshop, 1993), 192. (Main Rulebook)
• Martin Dougherty. A Guide to Star Systems (Mongoose Publishing, 2015), TBD.
• Marc Miller. T5 Core Rules (Far Future Enterprises, 2013), TBD.
• Author & Contributor: Lord (Marquis) and Master Scout Emeritus Adie Alegoric Stewart of the IISS