| Type | Alternate timeline phenomenon |
| Cause | High levels of solar radiation from solar flares |
| Duration | 14-20 months |
| Frequency | Every 27 years |
| Effect on society | Profound changes in architecture • Technological advancements in underground living • Reversed day/night activities • Significant cultural developments |
| Notable landmarks | Modernized undergound facilities • Adaptive nocturnal cities |
| Cultural adaptations | Nocturnal activities during flare periods • Growth of arts in nighttime subcultures • Development of underground agriculture |
| Influential scientists | Alternate Thomas Edison • Alternate N. Tesla • Alternate Ada Lovelace |
| Architectural developments | Special facilities for underground living |
| Technological advancements | Advanced solar protection • Underground electricity generation • Culture-preserving infrastructure |
