Humans
PUBLISHED
Most of us will know the poem: "30 days has September, April, June, and November. All the rest have 31, save February at 28. But leap year, coming once in four, February then has one day more."
The rest of this article is behind a paywall. Please sign in or subscribe to access the full content.It does imply that January, March, May, July, August, October, and December all have 31 days. However, these months are not the same everywhere in the world, and there are some places that have a 31-day month longer than the others. Can you guess which ones before we reveal them?
Let’s clarify that no, it is not January – no matter how we might feel.
There are two conventions at play that create the months longer than 31 days. One affects just over one quarter of all countries on Earth. It used to affect more, but a lot of countries have left this convention behind. An extra little hint is that the convention wouldn’t be the same in the Northern and Southern Hemispheres, and actually this longer month only happens in the north.
We are talking about daylight saving time.
It is not Benjamin Franklin’s fault
The US founding father has long been claimed to be the inventor of daylight saving time - he wrote a satirical piece suggesting that the Parisians could wake up earlier in the summer to save on candles and oil. Several others had similar ideas, but in a serious way, and in the first half of the 20th century it became commonly adopted.
While many countries no longer do it, several still do – over one-third of all countries in the world. In the Northern Hemisphere, there’s the US, most of Canada, almost all of Europe, as well as Egypt, and some Middle Eastern and Caribbean countries. In the Southern Hemisphere, there's Chile, Australia, and New Zealand.
How come this extra-long month only affects one-quarter of all nations when one-third use it? Well, not every nation switches between the two times in the same month. Europe, Lebanon, Palestine, Egypt, and Israel have their clocks go back in October, so their 31-day month is actually a whole hour longer.
The Southern Hemisphere countries all switch in April, and the US and the Caribbean nations switch in November, both 30-day months, so they do not get a 31-day-and-one-hour month.
And for all the other countries?
For all the countries in which October doesn’t get an extra hour, there is occasionally a month that is slightly longer: December. It is not longer by much, just one second, but it is an important second. It’s called a leap second, and they are used to make our clocks match the actual rotation of the Earth.
Our planet's rotation is not exact, and it does experience speeding up and slowing down. Depending on that, leap seconds can be added on June 30 or December 31. The last time one was added was December 31, 2016, the longest month for many countries.
