For the past couple of weeks, holiday lights have been shining at night at the Denver Zoo — a hint that the annual Denver Zoo Lights event is just around the corner.

Over 33 years, this event has become a tradition for many Front Range families.

More than 3 million lights (up by a million from past years) are being hung over the Zoo’s 80 acres.

Denver Zoo has decreased its energy consumption by 78% by switching to LED lights this year. The move will save the zoo $600,000.

The Zoo’s Environmental and Campus Services team will be auditing waste and finding ways to make the event more eco-friendly.

This is part of the Zoo’s effort to become a zero-waste campus by 2025.

“Throughout the event, the Zoo’s Environmental and Campus Services teams plan to trial new waste receptacles and conduct waste audits to gain an understanding of the Zoo Lights waste stream and determine areas of opportunity for supply chain changes or guest communication,” according to a statement from the Zoo.

Zoo Lights runs from Dec. 2 through Jan. 7.

A few special dates to consider: Nov. 20 is Adults-Only Night; Nov. 24-Dec. 1 are members-only dates; Dec. 2-Jan. 7 is the general admission run, and Dec. 31 is Sensory-Friendly Night.

Tickets are on sale to the general public now. Prices vary, and the Zoo expects the event will sell out.