Uranium, Plutonium & Solarium ores can be smelted in a furnace to produce Rods of their respective types, these are used as ship fuel.
Initially the player can use Coal as ship fuel; 1 Coal ore produces 2 units of fuel. Unrefined Wood can be harvested from Trees and converted to Coal in a Furnace, 10 wood = 1 Coal.
So 5 wood can be converted into 1 unit of ship fuel, the ship can hold 1000 units of fuel and has 6 slots for additional coal, uranium, plutonium or solarium.
You can put the ores or smelted rods into the ship fuel bay, each rod requires two ores, but currently the rods are worth the same as an ore.

Uranium ore produces 4 units of fuel.
Plutonium ore produces 6 units of fuel.
Solarium ore produces 8 units of fuel.

It requires 200 units of fuel to travel to any other star system, including stars in different sectors.
It requires 50 units of fuel to travel to a different planet within the same star system; but it only requires 1 unit of fuel if the planet is part of the local group of planets.

It's notable that there are links between some stars on the starmap; however this does not seem to have any special significance other than as constellation markings.