EtherAlchemist writes "National Geographic News reports in this story that a giant, peanut shaped asteroid known as 4179 Toutatis will pass within 1 million miles of Earth on Weds, the 29th. When it does, it will be the closest any known object of this size (3 miles) has passed near Earth in this century. No worry about impact yet, it should pose no threat until at least 2562. An interesting note: the asteroid believed to have caused Earth's biggest mass extinction is thought to have been between 3.7 and 7.5 miles as reported here in 2001." 2004 FU162 came closer
, but is a much smaller object.