Chewbacca no stranger than Sarah 

Coldplay frontman Chris Martin supports Nicole Kidman's choice to call her daughter Sunday and believes "Chewbacca" would be an OK name too.

Martin and Hollywood actress wife Gwyneth Paltrow, some may say, raised the bar on odd names four years ago when they named their daughter Apple.

The British-born musician believes the world should mind its own business.

"People make a big fuss over names," Martin said in an interview with America's Blender magazine.

"Names of babies, names of albums, names of bands.

"There's nothing weird about calling your baby Chewbacca if that's what you want to call your baby.

"It's no stranger than Sarah.

"A name is just a noise, and if you like it, then f...... what everyone else says."

The mystery of why Kidman and Urban named their daughter Sunday was solved by the actress' father, Antony.

He said the unusual name was inspired by Sunday Reed, a well-known arts patron in Victoria from the 1930s and he had told his famous daughter about the name.

Reed was Australian artist Sidney Nolan's muse.

Earlier this year, Kidman and Urban visited a Nolan exhibition at the Art Gallery of NSW and were entranced by a quote about birth from Nolan.

The quote, featured in the exhibition, read: "When you are young you are given a good view of life, because of your closeness to birth".

Meanwhile, Kidman has reportedly checked out of the hospital in Nashville, Tennessee, where she gave birth to Sunday.

The Oscar winner is said to be resting at the $A4 million, seven bedroom home the couple has on rolling green fields outside of Nashville.

Kidman's early exit adds credence to reports she gave birth to Sunday naturally, rather than Caesarean section.

Mothers undergoing a Caesarean usually spend several days in hospital.

Kidman's sister Antonia and mother Janelle were in Nashville for the birth, while Antony Kidman remained in Sydney to look after Antonia's four children.