Once a year, the enormous blue whale model that hangs from the Irma and Paul Milstein Family Hall of Ocean Life at the American Museum of Natural History gets cleaned – and it’s being livestreamed on YouTube. The event, aptly titled the “2016 Whale Wash” takes place over two days and started yesterday. The livestream will run today between 11 am and 12 pm (check back here at 11 am to see it above).

To give you a sense of why this blue whale is that famous – it’s the largest model of the largest creature that has ever lived on earth, says the museum. The life-size model weighs 21,000 pounds and is 94 feet long, and is based off of a female blue whale that was found off the coast of South America’s most southern point in 1925. It’s made of fiberglass and polyurethane and was installed in the museum in 1969. In the era of space exploration, knowledge of the deep seas was not nearly as advanced at the time. “Little was known about what blue whales looked like in their natural habitat,”says the museum’s Axelrod Research Curator Melanie Stiassny.

In 2003, Stiassny led the renovation of the hall, which included a rehabilitation of the whale to make it “more anatomically accurate than before,” says the museum. In the last fifty years, many more resources have become available for the study of the blue whale. As a result, the blue whale model at the American Museum of Natural History had a bit of a makeover: the eyes were made less bulging, the blowholes more true to nature, and made the tail more tapered. It also got a new paint job – which required 25 gallons of paint.

The blue whale model is cleaned using vacuums and long-handled brushes. Workers reach the whale by crane. In 2011, the museum released a timelapse video of the cleaning which you can watch here:

If previous years are any indication, there should be whale fun facts peppered throughout the hour long livestream.

Next, check out the Top 12 Secrets of the American Museum of Natural History.