To turn these astronomical ranges into a simple scale, we can use the
mathematical device of the **logarithm**. If we raise ten to some power
*x* to make a big number *N*, then the **log** of that big number
*N* is the power *x*:

Now let's review the **log** (base 10) of some example numbers:

Note that while you can take the log of a very small number, which will be
negative, you can't take the log of any **negative** number.

*J. Louie, revised 29 June 1998*

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