It's Sometimes Darkest Before The Dawn

For the most part, it doesn’t matter when you travel to see any of these by either the galactic or the local calendar. The Twin Worlds, the Shells of Thalíär, and the rest offer their spectacle to the curious eye at any time. Eliéra is the exception that proves this rule. You should visit Eliéra during its summer months, and preferably as close to midsummer as can be arranged, because that is when the Eliéran sunset is at its most spectacular.

The binary sunset of the Lumenna-Súnáris system is not in itself particularly spectacular; after all, binary – or higher-order – star systems are common in the inhabited galaxy, and indeed, many colonies are themselves located upon planets of binary systems. Everyone’s seen a binary sunset.

Eliéra’s, however, is unique, due to the combination of the unique parameters of its system, the width of the flat world, and the system its Precursor builders set up to provide it with its day-night cycle. During the months of high summer, the suns rise and fall in antiphase. As Lumenna (the system primary) sets, the full glory of the star-lit dusk appears for a matter of minutes, only, before distant Súnáris rises pale and wan, ushering in a faintly red-tinted twilight in which the stars fade, but do not vanish – until the morning, when Súnáris sets again, giving a dawn, too, of darkness and stars before the full light of day once more. This dual “star-flash” cannot be seen anywhere else in the known galaxy, a minor wonder of a greater work.

– The Twelve Wonders of the Galaxy, Ademone Kirvin-ith-Kirvin