Garden World

Garden Worlds are planets which meet a certain set of criteria for resemblance to Earth. The term is used to differentiate these Earthlike worlds from other Habitable Worlds. In general, the specific criteria needed to qualify a planet as a Garden World are rare in the universe, and only 7 Garden Worlds have been successfully surveyed.

Criteria
A planet must meet the following criteria to be classified as a Garden World:


 * The planet must meet all the criteria of Habitability Class A.
 * Surface Gravity must be within 10% of Earth Gravity.
 * Air Pressure at sea level must not vary from Standard Barometric Pressure (29.98 mmHg) by more than 10%
 * Year-Round temperatures must, at some latitude, remain between -30 degrees and 40 degrees Celsius, with nowhere on the planet exceeding -100 degrees or 60 degrees Celsius.
 * The planet must support an oxygen-generating biosphere.
 * The planet must have liquid water on at least 10% of its surface.
 * The planet must have an active liquid water cycle, with some region of the planet receiving at least 5 centimetres of rainfall annually.
 * The planet must receive at least 8 hours of direct sunlight at some latitude for at least half of the year. This implicitly means that the revolution rate of the planet cannot be less than 16 hours without accounting for axial tilt.
 * The planet must have stable and predictable weather patterns
 * The planet must have stable and predictable plate tectonics
 * An unprotected human inhabitant of the planet must not receive more than 250 millisieverts in radiation per Earth Year.