The Universe will be divided into Sectors, which are conglomerates of Systems. Each sector will have its average Threat Level, indicating to the player the difficulty level of that sector.
This does not mean that in sectors of a higher level of threat there won’t be Planets with Low Threat, they are just in smaller numbers there. This is also true for LowThreat sectors with HighThreat planets.
There are 6 Sectors in total with 6 Systems contained in each.
The average threat level of the sector is indicated before the Space Travel.