What time is it?! ⏰

Hi Reader,

I’ve been doing some research about Asia (ahem, if any of you have spent some time traveling around that part of the world I would LOVE LOVE LOVE to chat!), and while googling things like “what time is it in Tokyo right now” I found that when I looked at places in India the time was often 30 minutes off.

Initially, I was sure Google was wrong. I mean, if it’s 10:30 AM here, how is it 10:00 PM there? Come on Google.

But then, I started wondering how or why a place would be 30 minutes off (what feels like) standard time to me. And as I dug into this question, I learned some really cool things about the way time works around the world, which reminded me so much of math.

Let's start with a basic lesson about time zones.

Ideally, the sun should be at its highest point in the sky at noon. Since the Earth rotates, the sun is at the highest point of the sky at different times for different places around the Earth. It takes 24 hours for the Earth to complete 1 rotation, so with simple division we find that every 15 degrees we should have a new time zone.

360 degrees/24 hours = 15 degrees per hour

Time zones are set up based on meridians spaced 15 degrees apart (these are the vertical lines on a map or globe that slice the planet into long columns). Some European astronomers from the 1800’s decided that the Prime Meridian (where we base our time off) would be located at the Greenwich Observatory in England.

This is why we have GMT: Greenwich Mean Time (and why my timezone is GMT -7h). See? You’re learning so much already.

…but there’s more!

Basically, that’s how time zones work. Except, it isn’t.

Enter politics. It turns out, time and politics are deeply connected.

Many countries use the same time zone even if the country doesn’t fit perfectly into one 15-degree section of meridians, but a country might opt to be in a time zone that’s similar to their allies or trade partners instead of the designated zone based on meridians (hello Western Europe!).

In India, they use a time that is 30 minutes off GMT time because India falls between two meridians, so they took the average of the two times and ran with it (so when it’s 10 AM here it would be something like 8:30 PM there!).

Besides India, Venezuela has had years where their time was 30 minutes off GMT time (it’s currently in sync with GMT). Other fractional time zones include Iran, parts of Western Australia, a string of South Pacific Islands (some of which are 45 minutes off GMT), Sri Lanka, Afghanistan, and even a part of Canada!

Another anomaly is China (which, as a reminder, is a massive country that spans five time zones) which uses just one time, Beijing Time, for the entire country.

And, alllll of this just reminds me so much of math.

Math has beautiful “rules” that make the math world go round, until you start to look a bit deeper and you find that, in fact, 1+1 does not always equal 2. These bends in the rules, or flexible interpretations of time zones, are where learning becomes fun.

I love discovering these twists and turns because they get so many kids (and adults!) excited about things like time. Or geography. Or math.

So this week, spend 15 minutes with your kids looking at a globe (or the digital version of one) and discover a few time zones, with the help of Google. Don’t forget to stop in India!

To finding the curiosities around you,

Heidi

PS Want to uncover even more unconventional math facts?

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