One AU is the average distance from Earth to the sun - about 93 million miles, or 150 million km.
While most people would find it frightening to know that an asteroid could have hit the planet, dust and sand-sized particles routinely hit the Earth.
In 2013, Russian Federation was hit with an asteroid that has the same size as this one.
While 2017 AG13 would have caused minor damage if it hit Earth, the close call highlights the dangers of asteroids.
According to Eric Feldman, an astronomer with Slooh, the near-Earth object (NEO) was moving really quickly and had actually crossed the orbits of two planets - Venus and Earth.
2017 AG3 was approximately big as the meteor that hit Chelyabinsk, Russia in 2013.
What Could Have Happened If Asteroid 2017 AG3 Entered The Earth's Atmosphere?More than a thousand people were reportedly injured by flying glass and debris. Then, the crash damaged buildings and shattered windows.
Still, not knowing about near-Earth objects (NEO) until days before they fly close to the Earth is slightly concerning.
The asteroid was discovered by the Catalina Sky Survey, just before it intruded earth orbit. "There was a time where we didn't have a program to look for objects, and it was done privately", Bill Bottke, an asteroid researcher at the Southwest Research Institute tells Boyle.
The recently released "National Near-Earth Object Preparedness Strategy" highlighted our unpreparedness to defend Earth against a threatening asteroid despite recent efforts by scientists and advocacy groups to galvanize governments into action. (Or at least we hope we're tracking all of them).
Although it may be of some use or significance for Earth inhabitants, NASA has refused to fund a mission to spot and predict the entry or approximation of near-Earth objects, which would require sending a specialized satellite to capture and locate them from afar. Millions of asteroids are believed to cruise through the space in our planet's neighborhood.
Last December, Dr Joseph Nuth, at NASA's Goddard Space Flight Center in Maryland, warned at the annual meeting of the American Geophysical Union that we are unprepared for an asteroid strike.