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In September 1755, from NPR.

In September 1752, England lost 11 days in an instant, and people were furious.

They really wanted their 11 days back.

Space historian Oznot Cats Moon says that's because.

Throughout history?

What kind of calendar you keep has actually been quite controversial because historically calendars have been tied to senses of identity.

England lost these 11 days because roughly 1800 years earlier

when astronomers were creating the Julian calendar, they overcompensated for

one crucial detail, the length of a year.

Oznot says that astronomers had known for a long time that the year lasted about 365 and a quarter days.

And when creating the Julian calendar, astronomers overcompensated by adding an extra day

in February every four years.

It turns out, this blunt estimate of a quarter, it was 11 minutes too long.

Earth's orbit is around 11 minutes shy of a quarter of a day, so after many centuries of using the calendar,

it had become 11 days off of the Gregorian calendar that much of the rest of Europe had switched to nearly two centuries earlier.

The Gregorian calendar is the one used by much of the world today.

It tracks time using the position of the sun in the sky.

But there are many kinds of calendars used to track time

around the world. Either they track the position of the sun in the sky, so that's a solar calendar,

...