Ronna, quetta, ronto & quecto: As measurements get new prefixes, Earth now weighs 6 ronnagrams

Four prefixes approved at General Conference on Weights & Measures last week. Until now, yotta & yocto were largest & smallest prefixes.

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Representational image of Earth | Commons
Representational image of Earth | Commons

Bengaluru: Over the weekend 4 new members have been added to the weights and measures family for the first time in 30 years. Ronna, quetta, ronto and quecto joined their well-known siblings kilo, mega, milli and micro to help succinctly describe the weight of our planet and the particles of our visible world.

The new weight of Earth now is six ronnagrams instead of 6,000 yottagrams and Jupiter is approximately 2 quettagrams instead of 1.9 million yottagrams, while an electron’s mass is now 1 rontogram or 1 rg instead of the previous 0.001 yoctograms.

The new prefixes for the International System of Units, also known as the metric system, were approved by a unanimous vote at the General Conference on Weights and Measures (CGPM) last week from representatives of 64 nations. 

The new prefixes for units measuring larger quantities are ronna (one followed by 27 zeros) and quetta (one followed by 30 zeros), while at the other end of the scale, ronto (ten to the power of minus 27 or 27 zeros after decimal point) and quecto (30 zeros after decimal) have been added. These are the first additions of prefixes to the list since 1991 and are expected to be the extremes for another 30 years. 

According to Richard Brown, Head of Metrology at the UK National Physics Laboratory (NPL) and lead scientist on the proposal, these names were chosen so as to be able to use the letters R and Q in short forms as they haven’t been used for other prefixes. Ronna and quetta are indicated by R and Q, while ronto and quecto by r and q. 


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A total of 24 prefixes

With the addition of the new names, there are a total of 24 prefixes — quetta, ronna, yotta, zetta, exa, peta, tera, giga, mega, kilo, hecto, deca, deci, centi, milli, micro, nano, pico, femto, atto, zepto, yocto, ronto, and quecto. 

Previously, yotta (indicated by Y, with 24 zeros) was the largest prefix, while yocto (indicated by y, with 24 zeros after decimal) was the smallest. 

The addition of the new prefixes was driven by the increasing and growing requirements of data and digital storage, which has already been using the extreme prefixes yottabytes and zettabytes, UK’s National Physical Laboratory explained in a statement. It is also a testament to improvement in technology that enables scientists to observe the smallest of things and the largest of quantities — the entire observable universe today has a diameter of one ronnameter. 

The announcement was made a mere 3 days after the birth of the 8 billionth person on the planet. 

(Edited by Geethalakshmi Ramanathan)


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