I like CNN's Miles O'Brien a lot. He's one of the few news people who really gets it when it comes to space science, so I follow him on Twitter and befriended him in Facebook.
This morning he was looking for anecdotes or analogies to describe what a 'trillion' is. I Googled a few things and came up with some interesting facts, some of them distinctly astronomical.
Our national debt can only be described using trillions of dollars. So how much is that? Well, a tightly-packed stack of crisp new $1000 bills, totaling $5 trillion, would be 315 miles tall. The Space Shuttle, which orbits at about 240 miles above the earth, would have to go around our "debt stack." I repeat, that is a stack of $1000 bills, 315 miles tall.
If we wanted to pay off 5 trillion dollars at the rate of a dollar a second, it would take about 160,000 years. Hmm... that got me to thinking.
Astronomers have found it much more convenient to use terms like 'light years' and 'parsecs' to describe the unimaginable distances involved in astronomy. For example, our galaxy is about 100,000 light years in diameter.
A light year is the distance light travels, at 186,000 miles per second, in a year. 186,000 miles, times 60 seconds, times 60 minutes, times 24 hours, times 365 days...
So it would take 60,000 years longer to pay off the 5 trillion dollar national debt at a dollar a second than it would to travel at the speed of light from one end of our galaxy to the other!
Our national debt is truly an astronomical figure. Maybe it should be measured in light dollars.