In honor of the 50th anniversary of the International System of Units, PopSci is looking at the origin and continued preservation of five of our favorite standard units. By Sam Kean.

This is the first time that the International System of Units, or SI, has expanded since 1991, when the prefixes zetta-, yotta-, zepto and yocto-were added (SN: 1/16/93).

The metric system's governing body has added some new terms to help describe massive amounts of data. The General Conference on Weights and Measures last week added the prefixes "ronna" and "quetta." ...

NEW LARGEST AND SMALLEST STANDARD UNITS OF MEASUREMENT. The prefixes make it easier to express large amounts – for example, always referring to a kilometre as 1,000 metres or a millimetre as one ...

New unit measurement prefixes are added to the metric system The mass of the Earth can now be measured as 6 ronnagrams rather than 6,000 yottagrams. An electron's mass can now be said to be about ...

While most of the rest of the world uses the metric system (formally known as the International System of Units, or SI), the United States uses the U.S. Customary System, which—fun fact—is ...

That year, the International System of Units, or SI, was defined and adopted worldwide. You May Also Like. SCIENCE. Earth doesn't really have a second moon—but here's what would happen if we did.

For the first time in 30 years, new terms have been officially added to the International System of Units. The four new prefixes – ronna, quetta, ronto and quecto – describe very large and ...

Related: Meet the zeptosecond, the shortest unit of time ever measured This is the first time that new prefixes have been added to the metric system since the addition of zetta (10˄21), zepto (10 ...