Mercury

Mercury is the smallest and closest to the Sun of the eight planets in the Solar System, with an orbital period of about 88 Earth days. Seen from Earth, it appears to move around its orbit in about 116 days, which is much faster than any other planet. This rapid motion may have led to it being named after the Roman deity Mercury, the fast-flying messenger to the gods. Because it has almost no atmosphere to retain heat, Mercury's surface experiences the greatest temperature variation of all the planets, ranging from 100 K at night to 700 K during the day at some equatorial regions. The poles are constantly below 180 K. Mercury's axis has the smallest tilt of any of the Solar System's planets, but it has the largest orbital eccentricity. As such it does not experience seasons in the same way as most other planets such as Earth. At aphelion, Mercury is about 1.5 times as far from the Sun as it is at perihelion. Mercury's surface is heavily cratered and similar in appearance to the Moon, indicating that it has been geologically inactive for billions of years.

Mercury was colonized similarly to the second efforts upon Luna, as it is a very similar landscape, with similar problems. The city of Leviticus serves as the capital, with various other cities and fledgling settlements spread about the surface. The leading industries on the planet are the collection of helium-3 and iron and magnesium silicates, and the manufacturing of much of the equipment that researchers on Venus have designed for terraforming projects, since production of these things is not achievable in the aerostat habitats of the second planet. Power to the entire planet is supplied by solar energy, and Mercury has refined, and perhaps even perfected the technology for harnessing and using solar power. The planet is also utilized to test shielding and thermal regulation technology, due to the proximity of the planet to the sun, and the vast amounts of heat and solar radiation that would otherwise render the planet unlivable. Leviticus is a city based on its industries, and is reflected in the architecture, and citizens. The entire city can be compared to a factory district, and almost everyone works long hours, with dangerous machinery, to achieve a high level of production. The Dominion compensates their workers, however, with reasonable pay, and the living districts of the city are on the higher echelons of quality compared to the rest of the colonies. Other cities or settlements are usually based around the mining operations that provide the raw materials for Leviticus to do construction. The Leviticus spaceport is one of the largest spaceports in Sol, as most of the ships that it services are vast cargo freighters. A planetwide train system is still under development, but currently travels between the major cities of Leviticus, Pheriya, and Darro.