Sawyers World

Sawyers World

The original name was "Sawyer's World", with an apostrophe. This was later dropped. The dropped-apostrophe is common in many place names.

A habitable (terraformed) planet orbiting Alpha Centauri A, (Alpha Centauri A II)

First extra-solar planet settled by humans (but not first landed upon, see Kakuloa). The very early history of this is detailed in the book Alpha Centauri: Sawyer's World, although the actual naming doesn't take place until Alpha Centauri: The Return.

Cities

• Largest city: Sawyer City

Clock and Calendar

Time

• Year: 631.11 local days (so 631 days and a leap year every 9th year), 677.13 Earth days. (About 10 days shorter than a Martian year.)
• Rotation: 25h 44m 17s (solar, ie noon to noon), or 25.738 hours
• Calendar: week = 5 26-hour days plus 2 25-hour days, with every 4th weekend having an extra hour.
  • 12 months, 5 of 52 days, 7 of 53 days, similar alternating pattern as Earth western calendar months.
  • Alternate one: 21 months, 10 of 29 days, 11 of 31 days, alternating.
  • Alternate two: 21 months, 20 of 30 days, 1 (last of the year) of 31 days.
  • Earth calendar and time (UTC -- which is now becoming truly universal) is also maintained for reference (file timestamps, etc.)

Physical Characteristics

Size

• Radius: slightly larger than Earth, about 1.05 E, 8400 miles diameter (8320 miles)
• Density: slightly lower than Earth, about 5.2 gm/cm3, similar to Venus (5.23 gm/cm3)
• Gravity: slightly lower than Earth, about 0.99 g (9.7 m/sec2) (0.986 g, 9.682 m/sec2)

(But escape velocity slightly higher, due to 1/r-squared: 11.42 km/sec vs 11.18 km/sec, and get a 0.41 km/sec boost from rotation at equator (vs 0.44 on Earth)

• • Specifically, Ve = 11.49 km/sec, rotation boost = 0.45 km/sec at equator, 0.32 at 45 deg lat.

Habitable zone is ~1.17 to ~2.05 AU, orbital period ~1.2 to ~2.8 Earth years. Sawyer's World distance and year about one-and-two-thirds of Earth's, roughly in the middle of the HZ. Orbital period is 1.479 Earth years.

• Year is 12962.7 hours, = 540.11 Earth (24h) days, = 503.641 Sawyer's 'solar' days (504.641 sidereal days).
• Rounding to 504 requires an anti-leap year every 3 years, skipping one every 5th leap year.
• Calendar is 18 months of 28 days, this is very close to 30 Earth days (720.66 hours vs 720 hours). In an anti-leap year one month has only 27 days.
• Orbital distance is ~1.34 AU, so together with the star's luminosity of 1.519 sol, it gets about 84.6% as much sunshine (per square meter) as Earth. The planet would thus be on average somewhat cooler than Earth, but in temperate latitudes this is offset by a smaller axial tilt (16 degrees vs Earth's 23) which reduces seasonal temperature swings, although it is colder at the poles. The atmosphere is also thicker, increasing greenhouse effect. The longer year also makes for a longer growing season (but also a correspondingly longer winter).

Sources

• The Chara Talisman ("we're here 26 hours a day")
• Alpha Centauri: First Landing (discussion of planetary parameters on initial survey)
• Alpha Centauri: Sawyer's World