Science/mathematical question

I read that Europas atmospheric pressure is 10 to the negative 12 times that of Earths. What does this actually mean?

Edit; just in case: It means that for every atom that Europa has in its atmosphere Earth has one-trillion atoms. If you meant what does 10⁻¹² mean then read on.


Large numbers are hard to read and write, so instead of writing them out in full we use a short hand called scientific notation. If I want to write the number 13,650,000,000,000,000,000 I recognize that this would be the same as 1.365 times 10,000,000,000,000,000,000.

I further recognize that 10,000,000,000,000,000,000 is the same as 10 times 10 times 10 times 10 times 10 times 10 times 10 times 10 times 10 times 10 times 10 times 10 times 10 times 10 times 10 times 10 times 10 times 10 times 10 times.

We also have a method of rewriting repetitive multiplications. We write the number we are multiplying, 10, and in a superscriptwe write the number of times we multiply it; in this case 19: 10¹⁹. We call the superscript value the exponent.

Taking us back up to the first paragraph we can now write 1.365 • 10¹⁹. This is easy to write and easy to compare to other big numbers.

Which is bigger 248,100,000,000,000,000 or 13,650,000,000,000,000,000; against, 2.481 • 10¹⁷ or 1.365 • 10¹⁹ The latter is over fifty times larger than the former — in my head.

If I write out a table that looks like this:

100,000 = 10⁵
10,000 = 10⁴
1,000 = 10³
100 = 10²
10 = 10¹

What would you suppose we'd do next? Why not continue the pattern?

1 = 10⁰

We've gotten to this patten by looking at the decrease in the number of zeros. We can't have less than no zeros. But there is something else that we didn't write down that if we did write it down we will see another pattern we could follow: The decimal point.

1,000.0 = 10³
100.0 = 10²
10.0 = 10¹
1.0 = 10⁰