According to this blog post, the key factor is whether a treaty relinquishing control of the British Indian Ocean Territory is signed.
Resolution Criteria
Resolves YES if, in 2025 (GMT), there is a moment when it is nighttime (i.e. between sunset and sunrise) for all territories under the control of the United Kingdom. Resolves NO if this never happens.
General policy for my markets: In the rare event of a conflict between my resolution criteria and the agreed-upon common-sense spirit of the market, I may resolve it according to the market's spirit or N/A, probably after discussion.
Update 2025-12-04 (PST) (AI summary of creator comment): If a treaty regarding the British Indian Ocean Territory is signed in 2025 but the bill to give it effect is not passed by the end of 2025, the market will likely resolve NO. Resolution is based on the actual territory of the UK at the time of sunset in 2025, not merely whether a treaty has been signed.
1,000Treaty signed 22 May 2025. However a bill is going through parliament to give it effect AIUI and may well not be completed in 2025.
@Conflux If Bill is not passed by end of 2025, does this resolve yes or no?
@ChristopherRandles It resolves based on the territory of the UK in 2025 at the time of the sunset. So I think prob no.