Sign of intelligent life! The yellow glow indicates the presence of emissions.
Solar systems with high electricity consumption will send out emissions that can be detected by cities in other solar systems. The strength of the emissions is affected by the total amount of electricity used by all cities and spacecraft in the solar system.
A city's chance of detecting emissions from other solar systems depends on the city's deep space sensor range defined by the radar and the strength of the emissions.
Solar systems produce emissions when cities and spacecraft consume electricity. The higher the solar system's total power consumption is, the higher the emission strength and thus the further away the solar system can be detected from.
Underwater cities emit 1/10th the city's normal emission output thanks to the insulation caused by the water.
Emissions Detection Range
The maximum range of emission detection depends on the furthest deep space sensor range of any airport radar or military radar.
Any solar system outside this range cannot be detected, no matter how high the emission output of the solar system is.
A spacecraft with sensor will also detect emissions from nearby solar systems, but the spacecraft will have to remain in the same solar system for about 6 hours for all possible emissions to be detected.
The emissions are affected by light lag, meaning that they travel at lightspeed. The further away the emission source is, the longer it takes for the emissions to be visible by the detector.
The average light lag for emissions is just a few hours.
Quotes from patch notes
| Related patch notes
|Update 2013-03-07: Detect Cities in Unexplored Systems
- Star map now shows a yellow glow around unexplored solar systems from which city emissions have been detected.
- Solar systems emit a signal based on the hourly consumption of power by all cities in the system. The strength of this signal determines the maximum distance at which the system can be detected.
- Cities with sensors detect the signal emitted by solar systems. Detection range of cities is 10pc per sensor tech level. City sensor tech level is the highest tech level of the airport terminal and any bases.
- Detected solar systems are remembered for up to 48 hours after the last signal is detected from that system.
- This information accumulates as the servers run. It may take an hour or two after the servers start before you start detecting city emissions. This will always be the case as this information is not stored.
Update 2013-08-21: Empires Too Vulnerable to Raiders
- Empires were reported to be too vulnerable to raiders based in the void. There is no way to know where the raiders came from or went.
- System emissions are based on power consumed in a system. Power consumed by ships is now added to that signal; previously the signal was only based on power consumed by cities.
- This is a step toward solving the problem, not expected to eliminate the problem. I am still considering other steps.
Update 2015-03-03: System Emission/Detection Range
- System emissions are detectable too far away for the more compact area we are playing in. The number of detected systems can be overwhelming.
- City signals can no longer be detected as far away.
- City sensors no longer have as much range for detecting city emissions.
Update 2017-02-12 and 2017-02-13 Qt 5.8: Undersea City Power Emissions
- Undersea cities now emit 1/10 of the signal due to their power consumption, for remote detection purposes.
Update 2018-08-14: Energy Emission Detection
- New style cities do not detect energy emissions from unexplored systems, for the star chart.
- New style cities now detect energy emissions using their airport radars and military radars.
Update 2018-08-14: Emission Detection Signal Strength
- Can the energy emission detected on unexplored systems give an indication of signal strength?
- A signal strength bar now appears below the yellow dot painted on unexplored systems where energy emissions have been detected.
Update 2018-09-17: Store Emission and Detection Info
- The emission and detection information resulting from power usage in solar systems is not saved between server restarts. It takes a long time to accumulate.
- Emission and detection information is now saved and restored between server restarts.
- This also flushed out a minor bug that caused solar systems to be updated to the client at times when no update was needed.
Update 2018-09-19: Spacecraft Detect Emissions
- Someone suggested that spacecraft participate in the detection of system emissions.
- Spacecraft with sensors will now detect emissions from solar systems.
- Deep space detection range is reported on the design analysis.
- As with cities and buildings, emissions from the solar system containing the ship are not detected.
- Systems only emit their signal once per six hours. A spacecraft would have to loiter that long in a system, to detect every possible signal.
- The ship itself does not indicate when it detects a signal. It just responds appropriately so the star map gets updated.