What is it called for a period of billion years?

Answer 1

There will be a lot of noughts in this answer!

In the USA, a billion ('years' or anything) is one thousand million i.e. 1,000,000,000 or 109. (1,000 x 1,000,000)

In the UK, 'a billion' used to mean 1,000,000,000,000 (1012), being a million times a million (1,000,000 x 1,000,000). But the American meaning, i.e. one thousand million (109) is now in more general use in the UK.

The fact that Britain now has two alternative meanings for 'billion' can cause confusion and misunderstandings.

British people seem increasingly aware that non-British people mean 1,000,000,000 (109) when the word billion is used, and they usually understand that 'a foreign billion' is therefore less than an 'old' British billion! However, for the avoidance of doubt, most financial and scientific texts make the real quantity clear by inserting the actual numerical value near any usage of the word 'billion(s)'.

Why are there two different quantitative meanings of 'billion' ?

Historic custom has led to different 'number terminology scales' being used in different countries. i.e.

# the 'short scale' is used in the USA, and every new 'quantity name' means a one thousand (1,000) times increase in value over the previous 'quantity name'.

# But the 'long scale' is used in many European countries, where the values underlying their names increase by a million (1,000,000) times the previous 'name'. How does this work?

* The 'short scale' starts with one thousand (103), the next 'level' is 1,000 x 1,000 and is called a million (106). The next level is 1,000times a million (=1,000,000,000 or 109) and is called a billion. And a trillion is a thousand billion (1012) * The 'long scale' starts at a million (1,000,000 or 106). The next level is a a million million and is called a billion (1012), and a trillion is a million billion (1018).

In the UK, the long scale (1012) system was used for many centuries, but in 1974 the UK government officially adopted the American short scale system, and since then all official publications and mass media now use this basis as a matter of standard 'style'.

IN VIEW of the vast differences in magnitude between the two scales, users of the terms billion, trillion etc must ensure that they make clear the true numeric value of the actual quantities which the words are intended to convey. Similarly, readers and listeners must also check that they understand which values the writers/speakers really mean when they use terms such as billion and trillion.

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Use of the word 'billion' in countries other than US or UK:

# Many countries use their equivalents of the word billion to mean the long scale values (1012). e.g. Venezuela, Chile, France, Germany, Italy, Poland, Switzerland, Finland, Sweden, Colombia, Netherlands, Norway.

# Most English-speaking countries, and a few other countries, use billion in the short scale (109) sense. e.g. Australia, New Zealand, Brazil, and English-language speakers in Hong Kong, Singapore and in the Philippines.

---- CONCLUSIONS: * The expression 'a billion years', when from a UK source in an astronomical or scientific context, and when used since 1974, or if the term is being used by an American, or has a USA source, then it would most probably mean 1,000,000,000 (109) years.

* If the context indicates that the source is UK based and if the date of publication is pre 1974, then it is likely that it means 1,000,000,000,000 (1012) years. * For all other situations, countries, language groups, time periods and contexts, further clarification should be obtained in order to determine which particular length of time (109 or 1012 years) is meant by 'a billion years' or the foreign language equivalent of this expression.

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Answer 2

A billion years. In countries where "billion" has a different meaning, a thousand million years, or a milliard years. The term "gigayear" could be used, and sometimes is, but it is not very common.

Answer 3

billion years is called an aeon

now tell everyone that

Answer 4

A billion years is called an eon. I usually call it "gigannum", but that's just me, as so you see terannum, etc.

Answer 5

A billion years is referred to as an eon.

Answer 6

giga year