- var_dump: documentation ( source)
<?php
$date = new DateTime( '2100-06-02T00:00:00', new DateTimeZone( 'Australia/Sydney' ) );
$date->setTimezone( new DateTimeZone( 'UTC' ) );
$date2010 = new DateTime( '2010-06-02T00:00:00', new DateTimeZone( 'Australia/Sydney' ) );
$date2010->setTimezone( new DateTimeZone( 'UTC' ) );
var_dump( $date, $date2010 );