Sir David Attenborough's accessible and compelling programmes have shown audiences not only the diversity of life on Earth but also the changing technologies used to bring that life to television screens.
Here are some of his most memorable moments:
1. In the 1979 series Life On Earth, Sir David encountered a family of mountain gorillas in the volcanic forest on the border of Rwanda and Zaire. In a clip that has been voted one of the top TV moments of all time, one young gorilla lies across his body, while just at the edge of the picture you can see the baby gorillas who were busy removing his shoes. The 13-part series featured footage from 30 countries. More than 500 million people tuned in - 11.4% of the global population.
2. In 1984, Sir David became one of the first underwater presenters as he observed the grey reef shark in The Living Planet. Developments in full face plates allowed him not only to be able to deliver his commentary but to be recorded clearly.
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3. Also in The Living Planet, he presented in zero gravity from the Nasa experimental plane, nicknamed the "vomit comet". He bounced and floated around as he described how we take gravity for granted, before ending his commentary completely upside down.
4. In 1990, he took viewers swimming with dolphins in Trials Of Life, to show us something of the body language and sounds that dolphins use to communicate, strapping on his scuba diving suit to eavesdrop on their conversations.
5. In The Life Of Birds in 1998, he clutched his binoculars as he walked carefully towards a lyrebird in South Australia and marvelled in delight over its extraordinary impersonation skills. The bird's camera shutter, car alarm and chainsaw calls were its attempts to outdo rivals and attract a mate.
-- BBC Earth (@BBCEarth) April 13, 2016
6. In State Of The Planet in 2000, he revealed the microscopic world which is well beyond human perception, using a powerful scanning electron microscope that magnified the image of a pin 10,000 times.
7. Sir David's sheer excitement at the moment a huge blue whale surfaced during 2002´s The Life Of Mammals was heart-warming to witness. He is shown clinging on to his little boat, which is dwarfed by the 30m whale, the largest animal ever known to have existed.
8. Also in The Life Of Mammals, Sir David visited a group of orphaned chimps which were being taught the survival skills needed to live in the wild. As his boat neared the landing point, an enthusiastic chimp jumped straight in to greet him. He later enjoyed a nut-cracking session with a group of dexterous mammals.
9. Another spectacular moment in the series came when Sir David trudged slowly through knee-deep snow to come face to face with a Siberian tiger in captivity.
10. A sequence in Life In Cold Blood in 2008 used beautiful slow motion to show the diversity in size, shape and ability of frogs and toads. Sir David lay on the floor of a Madagascan rainforest with a tiny pygmy frog resting on his fingertip to marvel at the "miracle of miniaturisation".
11. In Frozen Planet in 2011 he became the oldest person to visit the North Pole, venturing into high altitude and extreme cold at the age of 84.
:: Inspiring Attenborough: Sir David At 90 will be broadcast on BBC One on May 8.