The data comes from public NASA records and tracks 17 of the closest astronomical menaces to Earth that are greater than 3,280 feet across – that is, big enough to do some catastrophic damage. The closest rock to come screaming past Earth – 1999 AN10 – is more than 3,600 feet across but won't buzz the blue marble until 2027. The largest object on the chart, known as 433 Eros, will come around much sooner, in January of 2012.