Equinox Adventure

Craft a sci-fi or fantasy story based on the premise of a once-in-a-millennium celestial event happening on the March Equinox.

This prompt invites you to create a wonderful tale of intrigue and adventure. Start with the unique celestial event that only happens every thousand years during the March equinox. This celestial event is said to open a door to another dimension, or perhaps it awakens a dormant creature, or grants unimaginable magical abilities. How do the protagonists stumble upon this? How does it change their lives? The sky is not the limit here, let your imagination take flight.