Sunday was an Earth Colony world upon which the Doctor encountered the Swamp Monster.
Astronomical Data
Sunday orbited a bloated orange star one hundred Light years from Earth. The system contained at least two gas giants and some asteroids. Sunday's rotation period was approximately 12 hours. It had .9 Earth normal gravity. Sunday had at least one moon that was orange due to the sun's light.
Climate
Sunday was a very warm and wet planet. It often rained there and it had purple skies.
Geography
Sunday was almost entirely covered in vast, unbroken oceans. A few islands of varying sizes lay on the equator. These islands were covered in large swamps, forests and a number of rivers. The forest closest to the human settlement of Sunday City was known as the Slim Forest.
Native Flora and Fauna
Sunday had a vastly varied ecosystem, even before the arrival of human colonists. The planet was home to water pigeons, Sundayan 'gators, and Sundayan otters to name just a few. The Slim Forest also contained a variety of trees, including salt-trees.
History
The planet was first colonised by humans on a Sunday in the year 2107 by 800 colonists from Earth. The colony was established as part of the First Wave of human colonisation. They launched from the spaceport in Mbandaka in the Democratic Republic of Congo in a mark II world-builder called the One Small Step. They established Sunday City along the banks of a river. and prepared for the next group of colonists.
However, three months before the arrival of the Doctor, the planet passed into the orbit of a recently destroyed asteroid. Most of the pieces of the fragment cloud burnt up in the atmosphere, but a few struck the surface. One struck the ocean, one kilometre from the shore and six kilometres from Sunday City. The resultant tidal wave raced up the river and struck the settlement, washing most of the buildings and the One Small Step away. More than half of the colonists died in the disaster.
Upon the arrival of the Doctor and Martha Jones, they lent assistance to the colonists in dealing with the emerging threat of the Swamp Monster that had arrived on the asteroid. (NSA: Wetworld)