Buy the ticket online spaceneedle.com but verify first by calling them ahead of time because it could change due to the health and safety situation.
Make reservation 4 next day.
Tickets for sunset sell out quick. I was able to snag tickets for 745-8:00 pm, which allows you stay until it closes.
We went after 6pm last week. I believe they close at 7pm.
Thanks! Your answer is awaiting moderation.