The 15th annual world famous Christmas tree lighting ceremony "Christmas in Rockefeller Center" will telecast live on NBC and livestream online on Wednesday, Nov. 28 at 8/7c. Guests scheduled to appear include "American Idol" judge Mariah Carey, "The Voice" mentor Cee-Lo Green, Disney star Victoria Justice, Chris Mann, Rod Stewart, Academy Award host Billy Crystal and Bette Milder. The Radio City Rockettes and The Muppets will also appear. The event will unveil a holiday ornament-trimmed and well-lit Norway Spruce tree that is approximately 80 feet tall and weighs almost 10 tons, according to NBC. The tree was estimated to be 80 years old. It is reportedly decorated with 30,000 lights and topped with a Swarovski crystal star.