Starfall is a celebration of the yearly migration of spirits seen across the sky. It is so beautiful that even the members of the Court of Nightmares crawl out of Hewn City to look at the sky. It falls on the same day as Nynsar (a minor spring holiday to celebrate the end of seeding the fields and to pass out the first flower clippings of the season) and it is only possible to see it in the Night Court.
People celebrate Starfall by turning off all the lights and throwing a party in the House of Wind. They gather in the balconies and when Starfall begins, they dance and the music plays.
When Feyre attends, she stays up on a balcony where Rhys eventually comes to apologize for ignoring her. While they are talking about Starfall, one of the spirit-stars splatters onto Feyre, causing her to laugh. Presently, another, larger star sprinkles its glow all over Rhysand's left side, his face, and his left hand. Feyre, without thinking, steps forward, grabs Rhys's hand, and paints for the first time since Under the Mountain. She then looks up at Rhys and smiles, also for the first time. He is enraptured and asks her to smile again. They dance for the rest of the night.
Starfall is supposed to occur around the Spring Equinox.

Starfall from ACOTAR coloring book. (line art by Charlie Bowater)
Appearance
At first glance, Starfall looks like its name, a shower of shooting stars in the sky. However, they are actually spirits, as evidenced by the pale green light that splatters Feyre when a spirit on her.
Ties to the past
As Starfall was no secret to outsiders, Amarantha made sure Rhysand serviced her the entire night as she knew how special it was to him.
Rhysand says that every year thousands of spirits are migrating but every year they also decrease.
Quotes
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