Judging the size and value of the universe, as measured in starlight and grains of sand

Some things in nature are bigger than hen scratchings like this can describe.

Take the number “1 billion,” for example. Politicians talk about billions of dollars, astronomers talk about billions of stars. But how much is a billion, really?

Think of it this way. Say you were handed $1 million on the day Christ was born about 2005 years ago – the starting point of our calendar. Let’s say you were required to spend $1,000 every day, no more and no less (and no collecting interest in the bank). How long would your $1 million last?

Some quick arithmetic gives the answer: A million is a thousand thousand, so it would take 1,000 days to spend $1 million. Your money would be gone in less than three years. In cosmic time, a quick shopping spree.

Now, let’s say that on the same day, your friend was given $1 billion, and also had to spend $1,000 a day. How long would your friend’s billion last?

The answer: Today, early in 2006, your friend would still have nearly $270 million left. A billion is a thousand million, so it would take 1 million days to spend $1,000 a day. At this point, more than 700,000 days have passed since Christ’s birth.

A million, a billion – after a while it adds up to some big money. More than most of us make, and useless to fantasize about. In truth, the stars seem a lot closer to home than a million dollars.

Their beauty can be held in the palm of your hand, so to speak, even though their number escapes comprehension. For a while it was believed that the whole universe was a single group of stars circling together – one large galaxy. But in 1925, the astronomer Edwin Hubble showed that some fuzzy patches of starlight were their own groups of stars outside our group. In fact, he showed, they were themselves whole galaxies, like distant star-islands. As telescopes grew more powerful, the number of galaxies reckoned to exist also grew.

Some galaxies are believed to have just a few million stars. Others have trillions. In the Milky Way galaxy where we live, our sun is one of somewhere between about a hundred billion and a trillion stars. (Estimates vary. A trillion is a thousand billion.) The nearest large galaxy to us, called M31, is about 2.5 million light-years away, and about our size. On clear, dark nights you can make it out as a faint white blur if you know where to look in the constellation Andromeda.

Some astronomers calculate that around 100 billion galaxies are in our lines of sight. The highest estimate I’ve seen is 120 billion. Now, if all the galaxies averaged 1 billion stars each, that would mean 120 quintillion stars exist at any given moment in the visible universe, more than all the grains of sand on all the beaches of the Earth. And mind you, about 96 percent of the universe is invisible to us.

On a clear, dark night, you can spot about 7,000 stars, like a field of wildflowers, among the hundred billion or more stars in our one, average-size spiral galaxy. What is happening out there in those indescribable billions?

Your million dollars is chicken feed.