Pronunciation: (SEE-uhr)
Galactic Region: Perseus Arm
Galactic Branch: Sikhara Branch
Galactic Sector: N4
Star System: Sol
Distance to Sol: 197,000 miles
Radius: 1,145 miles
Surface Area: 16.5M square miles
Volume: 6.3B cubic miles
Circumference: 7,190 miles
Moons: Cara, Fain, Fiach

Siur is the second planet in orbit around Sol, sharing its orbit with Terra, an arrangement which cause Terrans to consider Siur to be a sister planet

From the perspective of sentient terran humanoids, Siur is the source of alot of speculation. In an opposite orbit, Siur remains out of view of Terra at all times, though the existence of the planet is known as its moons and their orbits have been plotted. It has similar appearance and size to Terra, though this is not known by Terrans. Despite the mystery, Siur is considered to be a “sister” planet to Terra