The last time: science and measurement
5 closed last occurrences in science and measurement, most recent first.
| Question | When | What | Could it change? |
|---|---|---|---|
| When were the SI base units last redefined? | 20 May 2019 | The kilogram, ampere, kelvin and mole were all redefined at once | No |
| When was the last leap second added? | 31 December 2016 | A second added to the end of 31 December | Yes |
| When was an element last added to the periodic table? | 28 November 2016 | Nihonium, moscovium, tennessine and oganesson were named, completing row seven | Yes |
| When did the number of planets last change? | 24 August 2006 | Pluto was reclassified as a dwarf planet, leaving eight | No |
| When was the metre last redefined? | 1983 | Defined as the distance light travels in 1/299,792,458 of a second | No |
- When were the SI base units last redefined? 20 May 2019
- When was the last leap second added? 31 December 2016
- When was an element last added to the periodic table? 28 November 2016
- When did the number of planets last change? 24 August 2006
- When was the metre last redefined? 1983
Related pages
- Space 3 here
- Countries and borders 8 here
- Technology that stopped 8 here
- The natural world 5 here
- Everyday things 7 here