Sunday (planet)

Sunday, once proposed to be called Wetworld, was an Earth colony planet upon which the Tenth 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 twelve hours. It had .9 Earth normal gravity. Sunday had at least one moon that was orange due to the sun's light. (PROSE: Wetworld)

Geography
Sunday was almost entirely covered in a vast, unbroken ocean. 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. Sunday was a very warm and wet planet where it often rained. The atmosphere was humid and thick enough that flying birds would leave trails in their wake. The sky was purple. (PROSE: Wetworld)

Native flora and fauna
Sunday had a diverse ecosystem, somewhat akin to an Earth marsh. The planet was home to highly intelligent Sundayan otters, and Alligator-like creatures the settlers called "'gators". It was also home to many birds – including water pigeons, curvers, sea-waders, and a bird with "steel-blue wings". Sunday's waters housed wide variety of fish, including worms that buried into human skin, and one fish with razor-sharp teeth that reportedly wouldn’t let go of its prey even with its head chopped off.

The Slim Forest also contained a variety of trees, including salt-trees with soapy sap. There were also climbable trees with cage-like branches closer to the water's edge. The swamps of Sunday were knotted with dense roots from a variety of trees. (PROSE: Wetworld)

History
When the planet was first discovered by humans, the name "Wetworld" was proposed, as a contrast to the relative dryness of Earth. This would ultimately be vetoed by the human settlers who colonised it.

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. Settlers used quad bikes, and drilled for uranium which was intended to power their settlements once the uranium supplies from their ship, the One Small Step, were depleted.

In 2108, 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. Later this same year the old city was rediscovered, along with the wreckage of the One Small Step, when the water they were submerged under began to drain away.

Upon their arrival, the Doctor and Martha Jones lent assistance to the colonists in dealing with the emerging threat of the Swamp monster that had arrived on the asteroid. (PROSE: Wetworld)