Obtaining values from objects

Question

This code works fine and returns two StdClass Objects for each of my two posts:

        $children = get_pages($args);

        foreach ($children as $cake=>$element) {
            $args = array(
                          'post_id' => $ID
                          );
            $Comments = get_comments( $args );
        };

This is great. I get each comment's properties but I am only interested in the comment date. My desired output is:

$CommentDates = (date1, date2, etc) -- Eventually I'd like to get the most recent comment date.

My next move is:

        foreach ($Comments as $CommentObject) {
            $CommentDates = $CommentObject->comment_date;
        }

This returns only one date and it happens to be the second object's value.

However, if I simply echo this foreach, I get both dates.

foreach ($Comments as $CommentObject) { echo $CommentObject->comment_date; }