Color of ship trails

Ship trails have 4 main colors :
White/blue
Green
Yellow
Red

Please remember that players can set a custom ship trail in the space anomaly, and could have a different color of what is indicated here.

A ship with a green trail is an NPC ship.
Attacking it will trigger a space battle.

A ship with a white/blue trail is a player.
If the player has disabled PVP, you will not be able to attack them.

A ship with an orange trail is a squadron ship.

A ship with a red trail is a pirate or a sentinel ship.
Most of the time, you wanna destroy thoses as soon as you see one.

Players can unlock custom colors by completing Nexus quests at the space anomaly.
Here's an example of the gold trail :