Luna is Spanish for Moon, while it's thought Encinas is Javier's paternal surname
Now the name of the little one has reportedly been revealed – as Luna Encinas Cruz.
Luna is Spanish for Moon, while it's thought Encinas is Javier's paternal surname.
According to a Spanish newspaper, the couple's chosen name was let slip after Javier went to register their newborn.
39-year-old Penelope gave birth at Ruber Internacional Hospital in Madrid on 22 July – the same day the Duke and Duchess of Cambridge welcomed Prince George.
Penelope and actor husband Javier, 44, are notoriously private, and married in July 2010 in an intimate ceremony in the Bahamas after three years of dating. They went on to have their first child, 2-year-old Leonardo, in 2011.
Although Leo was born in Los Angeles, the couple chose to have their second child in Spain, their home country.
Earlier this year, Penelope opened up on how she'll be keeping her children out of the limelight, and wanting them to be 'as anonymous as possible'.
'I want my son and my kids - if I have more - to grow up in a way that is as anonymous as possible,' she revealed in an interview.
'The fact that his father and I have chosen to do the work we do doesn't give anybody the right to invade our privacy.'