A massive asteroid estimated to be 2.7 miles wide is set to make a ‘relatively close encounter’ with Earth on September 1. Dubbed ‘Florence,’ the huge space rock will pass just 4.4 million miles from our planet – or, about 18 times the distance between Earth and the moon. According to NASA, this is the closest an asteroid of this size has come since they first began tracking near-Earth objects, giving scientists an unprecedented opportunity to study it up close through ground-based radar observations. Asteroid Florence was first spotted in 1981, and is estimated to be 2.7 miles (4.4 kilometers) wide.