Festival of Reunion

When the aetherchasms initially became infested with daemons and were closed wherever possible, it led to a great amount of separation between family and friends who'd visited other worlds in a matter of minutes to find themselves stranded light-years away from home. For many mortals, this meant they'd never see their families again, but for eltari it was just a major inconvenience that could be rectified with time.
Nearby planets communicated with each other to in an effort to co-ordinate a series of mass exoduses, grouping the denizens of specific planets together to return in single ships. With how many had to be organised and sent out across the stars, and eltari preferred for piloting each ship, none directly went to Eltar. To this end, a ragtag group of eltari formed a daring plan to get back home. Using a shorter range craft, the eltari launched themselves onto passing comets, travelling across the stars on them before occasionally jumping to other ones. Whilst the journey was eventually successful, the careless and brazen nature of the venture ultimately led to it being a much longer and less time-saving method than they had anticipated.
After centuries of travel, when they finally made it back to Eltar they immediately began to indulge in celebrations, both out of relief at finally being home and to make up for the lost time they'd spent carefully rationing supplies and remaining diligent to avoid getting delayed further. From that point on, the eltari who had been part of that troubled voyage began celebrating the day of their return whenever a passing comet was in the sky. Over the years the tradition spread and grew, until eventually the passing of a comet becoame an official 3 day festival in a more widespread commemoration.
The festival of reunion encourages reconnecting with those who you've become distant from, whether friends or family. For the duration of the festival, most businesses are closed outside of limited travel services and people are instead encouraged to share their own crafts or make their own entertainment to share amongst friends, family and the community should they so wish. The festival is intended to be non-commercial, and so asking for money or service in exchange for goods is considered an insult, moreso than flat out refusing to serve or accommodate someone. It's meant to be a time of connection, sharing and joy, unhampered by such materialistic desires. (This doesn't, however, stop intrepid businesses from selling supplies for the festival ahead of time.)