That icon indicates ship or planet sensor range. It denotes how far away you can see enemy ships and colonies. The higher, the better. There is no downside to having larger sensor ranges (other than improvement maintenance costs).
Ships can get sensor package upgrades, which will allow them to see further, and make ideal upgrades for scout ships. These upgrades increase sensor range by:
- Long Range Sensors: +4
- Brainwave Sensors: +6
- Dusty Sensors: +8
Star Systems also have sensor upgrade packages, which the primary use of are for early detection and warning systems. The further away you can detect incoming enemy ships, the more time you have to move ships to defend the planet. These upgrades each provide 10% to sensor range:
- Collaborator Networks
- Signal Laser Array
Sophons also get a racial unique upgrade that provides +20% to sensor range: the Predictive Sensor Array.
Your heroes can also help increase the sensor range of planets with Abilities:
- Security Specialist: +4 to Star Systems
- Foresight: +2 to both Fleets and Star Systems (Only the applicable bonus is applied; can't use both at the same time with the same hero)
I couldn't find any data about star system's initial range, unfortunately. Each planet should have the same range, sans improvements/hero abilities, once they become full colonies. Note that planet influence increases with population; that's the colored circle around your planet; sensor range is the colorless circle around ships and planets.
I'm not entirely sure how you ordered your fleets, so I'll throw a bunch of fleet movement facts out and see if any resonate.
First, on travel speeds: String Travel (blue arrow number) is usually the fastest means of travel. It's possible that you've done research such that your Direct Travel speed is so much higher that your String Travel speed that this path is actually shorter.
Usually the situation is inverted and the String Travel is the "scenic" route, so my usual calculus got really tripped up by the picture. Herp and derp. In those situations, it's possible that the scenic route will be travelled more quickly than the "direct" intersystem travel (green arrow number), despite the longer distance. Your ship actually figures out the fastest path to its goal when you give it a movement order, so in that case the string path was faster. Paths can have a mix of Strings, Direct Travel, and Wormholes, depending on the geography of the galaxy.
Second, on orders: As noted, you can force Interstellar travel with Ctrl + Right Click, in case you want to bypass a particular system (such as flitting around a fleet too large to engage or opening new fronts). Direct Travel also allows one to pass through Influence borders, the colored auras emanating from planets, unlike String Travel. Certain diplomatic situations cause Influence to act as an impenetrable String Travel barrier. You can string together orders with Shift + Right Click, so you could have manually created the order to move in such a way with Ctrl + Right Click on Ita, Shift + Ctrl + Right Click on Quyos.
Conclusion: Excluding the research possibility and excluding that you did this manually and forgot about it, the pathing would seem inefficient.
Best Answer