This past Monday, Gwyneth Paltrow celebrated her 49th birthday. But she proved age is just a number with a photo she posted on Instagram for her special day. It shows Paltrow in a bathtub on a terrace.

Gwyneth Paltrow's nude photoshoot for her 49th birthday

The actress looks coyly into the camera, her legs hanging over the side of the tub. She  covers only the bare essentials with her hands, as the Iron Man actress is completely nude in the picture. 

Paltrow also appears to have done without make-up for the photo. Fans as well as celebrity colleagues raved about the snapshot. "I mean…. GODDESS. Happy happy birthday!!!" Charlize Theron commented. "Brilliant pic," Naomi Watts added.

In her nearly 50 years, Gwyneth has already achieved a lot. The actress was most recently successful as "Pepper Potts" in the Marvel films, and she won her Oscar for Shakespeare in Love back in 1998.

With ex-husband Chris Martin, she has two children, daughter Apple and son Moses. She is now happy with husband Brad Falchuk.

You can also click here to see our picks for Paltrow's best movies!