[PHP] Why a script belong to user 'root' and the folder this script create is belonged to user 'nobody'?

[John . H]

My php program whose owner is root:

<?
   mkdir('test',0777);
?>

and the folder 'test'  's owner is 'nobody'?
why?should the folder belong to 'root' too?
By the way,the safe mode is turned on.