Sports Illustrated: Christie Brinkley praised for posing aged 63

Christie Brinkley has proved age is just a number by appearing on the cover of Sports Illustrated's annual Swimsuit Issue.

This year's cover sees the 63-year-old posing alongside her two daughters - Sailor Brinkley Cook, and Alexa Ray Joel.

Brinkley posed with Alexa Ray Joel, 31, and Sailor Brinkley Cook, 18

Writing on Instagram, Brinkley said: "Thank you Sports Illustrated for sending the powerful message that good things come in packages of every size and we do not come with an expiration date!"

Christie appears to be literally walking on water in the photo - something she referred to in her Instagram post.

"My kids think I walk on water, so let's not mention the apple box concealed just under the surface," she joked.

Alexa Ray is the only child of Christie Brinkley and singer Billy Joel

Christie shot to fame after appearing in Sports Illustrated in the late 1970s and went on to become well known as an actress and TV personality.

She continued to be a successful model, appearing on the cover of Playboy and Men's Health.

In 1985, she married Uptown Girl singer Billy Joel, who is Alexa's father. The couple divorced eight years later.

What is Sports Illustrated?

Christie has appeared on three previous Sports Illustrated covers

• Sports Illustrated is a weekly US magazine which has been running since 1954.

• Being featured on a cover is a huge deal, and carries the same prestige for a model as appearing on the Rolling Stone or Vogue front cover.

• It is especially renowned for the annual Swimsuit Issue, which comes out every February.

• Christie Brinkley has previously fronted the swimsuit issue three times before - in 1979, 1980 and 1981.

In its editorial, Sports Illustrated said Brinkley was "out to prove that age is nothing more than a number".

Speaking to People, the model said: "When I turned 30, I was like, 'This is the last time I'm posing in a bathing suit!'

"When this issue comes out, I'll be 63. I thought, 'those days are over'. But to get to do it with my girls, I thought, 'one last go!'."

Her daughter Sailor, 18, said appearing in Sports Illustrated "has been my dream since I popped out the womb" in a post on Twitter.

The images received a warm response on social media - although some questioned whether posing at an older age should be considered an achievement.