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Asteroid '13: If Earth Was the Size of a Basketball...

By Andy Cox
Published Feb 18 2013 04:44 PM EST

People have a hard time comprehending the size of things we don't encounter in everyday life. These days someone is more likely to compare the size of something to an iPad than to a breadbox, but we still can't often grasp the magnitude of the distance from the Earth to the Sun or the radius of a hydrogen atom. It often helps to put things into a scale that we can better understand.

For example, the asteroid 2012 DA14 will make a close encounter Friday (Feb. 15 around 2:24 p.m. EST) with Earth. There is no risk of the asteroid impacting Earth, but it's difficult to visualize exactly how big it is and how close it will come. NASA has published images showing 2012 DA14 passing within the "geosynchronous ring," but that's still a concept foreign to most. These kinds of images also often unintentionally misrepresent the relative sizes of the objects in question because of the vast scale differences, further confusing comparison.

I tried to find a good scale we can use to better grasp the 2012 DA14 close encounter and, in the process, perhaps better understand astronomical distances. While it's not perfect, the analogy I came up with keeps things on a good human scale with references to objects most people can easily visualize.

(MORE: NASA Cannot Monitor All Asteroids)

Imagine Earth as the size of a regulation NBA basketball (about 9.5" diameter) placed directly underneath the basket. At that scale, the Moon would be about the size of a tennis ball (about 2.5" diameter) sitting on the NBA three point arc (23.75 feet from the center of the basket).

So far, so good. The orbit of geostationary satellites that provide much of our communication and weather observations would be in a ring around the basketball extending just over 2 feet - roughly 26 inches - from the surface of the ball. For comparison, the typical orbit of the space shuttle and International Space Station would be less than 1/4 inch away from the surface of the basketball.

Now for the main event. At this scale, 2012 DA14 would be smaller than a typical bacterium and pass by the surface of the basketball less than two feet - about 20 inches - away at the closest point. For basketball aficionados, that's about half the radius of the NBA restricted area under the basket.

The speed of 2012 DA14 at closest approach in our miniaturized world would be just under 2 feet per hour (actual speed: 17,450 miles per hour relative to Earth).

In case you were wondering, the Sun would be about the size of an eight-story building a little over 1 1/2 miles away.

(MORE: Latest space weather updates from The Weather Channel)