It brings back the Sparrow Racing League and adds a bunch of new Sparrows and other Gear.
Along with new Quests, there will be new Bounties, a new Record Book with challenges, two new Sparrow racing tracks on Earth and Mercury, and a new game mode called Strike Scoring.
As always with these events, players will be able to find new Ornaments, consumables, Shaders, emblems, Emotes and so forth.
Here's the PSX trailer:
The Dawning will run until January 3rd. It's kind of a weird name, I think, but it's always nice to have an excuse to jump back into Destiny for a bit.