The Sphere is the "home system" where all captains begin their career. Though there are various factions vying for control of the various systems the Sphere is a relatively safe (as safe as space exploration can be) place to explore the various career paths a captain can embrace.
Here follows a description of the map of Sphere, for the benefit of those who cannot use the graphical map.
The systems can be divided between an inner ring and and outer ring, with four spokes between the rings.
The inner ring clockwise is Kelsey, Grantham, Palham, Descarte, Fieron, Drakos, Lorat. Kelsey is in the south and Descarte and Fieron are in the north.
The outer ring clockwise is Palolon, Yaralista, Sabot, Errat, Castalan, Umbari, Talsamar, Uskosia, Vesesia, Qarenil, Taithinarl, Phidarin, Sharaia, Undararnya, Tig. Palolon is in the west and connects to Forge galaxy. Vesesia is in the east and connects to Anvil galaxy. Sharaia is in the south and connects to the Expanse.
The south spoke is Kelsey, Franklyn, Iribis, Danar, Phidarin.
The west spoke is Kelsey, Ethan, Kell Expanse, Undadarnya.
The north spoke is Descarte, Bedlam, Kendra, Sunrise, Vassa, Ichelon, Errat.
The east spoke is Fieron, Kilby, Plarus, Tanari, Talsamar.
Many systems are on spurs off these main routes.
In the north, Gainsboro, Ferra, Spire, and Joycelyn are on a spur off Fieron.
Jaster, Thrace, Tomsk, Emmett, Kalisto, Danarius and Portal are on a branching spur off Descarte.
Ramora and Roleth are on a spur off Belam.
Jarrett is on a spur off Kendra.
In the south, Antioch and Hexham are on a spur off Kelsey.
Talon is on a spur off Iribis.
Feris, Farpoint 1 and Farpoint 2 are on a spur off Ethan.
On the outer ring, Terekant and Venugeth are on a spur off Sabot.
Heliopolis and Neonex are on a spur off Castalan.
Empereus, Telant, and Venara are on a spur off Taithinarl.
Atlantica, Medifield and Synchrus are on a spur off Tig.