Why does '08' generate error within the Eclipse?

I have a class with ' int = dia, mes e ano ' and in the other I'm calling them. But it caught my attention was that when I put the value '08' says

  

'The literal 08 of type int is out of range'.

But when I put 07, compile without problems.

I'll enter the codes:

    public class Data {
    int dia;
    int mes;
    int ano;
}

    public class DataTeste {
    public static void main(String[] args) {
        Data nascimento = new Data();
        **nascimento.dia = 08;**--este valor da erro, mas 07 p/baixo valida.
        nascimento.mes = 03;
        nascimento.ano = 1989;
    }
}