EARTH -WEIGHS- ENTRY : SIX RONNAGRAMS

Paris : Earth now weighs six ronnagrams; new metric prefixes voted in. So, say hello to ronnagrams and quettametres : International scientists gathered in France voted on Friday for new metric prefixes to express the world's largest and smallest measurements, prompted by an ever-growing amount of data.

It marks the first time in more than three decades that new prefixes have been added to the International System of Units [SI], the agreed global standard for the metric system.

Joining the ranks of well-known prefixes like kilo and milli are ronna and quetta for the largest numbers - and ronto and quecto for the smallest.

The change was voted on by scientists and government representatives from across the world attending the 27th General Conference on Weights and Measures, which governs the SI and meets roughly every four years at Versailles Palace, west of Paris.

The UK's National Physical Laboratory, which led the push for the new prefixes, confirmed that the resolution has passed in a statement.

The prefixes made it easier to to express large amounts - for example, always referring to a kilometre as 1,000 metres or a millimetre as one thousandth of a metre would quickly become cumbersome.

Since the SI was established in 1960, scientific need has led to a growing number of prefixes. The last time was in 1991, when chemists wanting to express vast molecular quantities spurred the addition of zetta and yotta.

A yottametre is one followed by 24 zeros.

But even the mighty yotta is not enough to handle the world's voracious appetite for data, according to Richard Brown, the head of metrology at the UK's National Physical Laboratory.

''In terms of expressing data in yottabytes, which is the highest prefix currently, we're very close to the limit,'' Brown told AFP.

''At the bottom end, it makes sense to have a symmetrical expansion, which is useful for quantum science, particle physics - when you're measuring really, really small things.'' [AFP]