Pharrell Williams asked for a "framed photograph of late astronomer Carl Sagan" on his rider.

The Happy hitmaker has very specific backstage demands at his concerts and, as well as a variety of premium alcohol and health snacks, he also always requests the picture of the pioneering cosmologist - whose research was crucial to the surface mapping of Venus and who also wrote papers on the existence of aliens.

The Smoking Gun website obtained a copy of Pharrell's 2015 rider, which included the Sagan image request.

Other items required for the 42-year-old musician include 12 cans of "super cold soda", a litre of Silver Patron Tequila, a bottle of Kettle One vodka, a case of alkaline water, a box Nilla Wafers biscuits, Cetaphil cleansing lotion, fresh ginger root, a jar of grape jam and one loaf of gluten-free bread.

The paperwork also states that Pharrell follows the Atkins Diet - famous for being low in carbohydrates - and needs his food "to be specifically cooked for him on a daily basis at the venues".

Pharrell requires that all advertisements inside the venue must be removed or covered because neither he nor his music is responsible for "hawking pizza or the local ambulance chaser".

Speaking about his admiration for scientist Sagan previously, the Get Lucky singer said: "When I look at that picture, I realise how lucky we all are ... to be on this planet and be able to do what we love to do every day. Seeing Carl's face reminds me of it."