# Longest Day of the Year

June 21, 2019

Today is the first day of summer! at least for the northern half of our planet. It’s also called the “summer solstice,” and it’s a special day in space: Today the top half of Earth is tilted toward the sun the most it ever is in a year. That gives us the longest day of the year, because the northern half is in the sunshine for longer. The farther north you go, the earlier your sunrise, the later your sunset, and the longer your day – in fact, the North Pole will have no nighttime for weeks! To see how this works, shine a flashlight at a ball that’s tilted as you turn it. Meanwhile, the southern half of our planet is starting WINTER. It’s the shortest day, with the longest shadows and total darkness at the South Pole. And in December, we’ll all switch!

Wee ones: Turn on a light, and hold a pencil standing straight up from the table. How long is the shadow? How does that change if you put the pencil on the floor or another surface, using the same light?

Little kids: If the sun rose today at 5:00 am for your grandparents and 1 hour later for you, at what time was sunrise for you?  Bonus: If a town near the North Pole has just 1 hour of dark tonight, how many hours of daylight do they have today? (Reminder: A day has 24 hours.)

Big kids: Today in Alaska the sun rose around 4:30 am, and won’t set until around 11:30 tonight! How many hours of daylight do they have today?  Bonus: If you stood outside today at solar noon (1:00 daylight savings), your shadow was the shortest of any time of year! If it was 25 inches long today and it’s 3 times as long at noon on the winter solstice (lowest sun of the year), how long is your winter shadow?

Answers:
Wee ones: See how the shadow changes with light at different angles!

Little kids: 6:00 am.  Bonus: 23 hours of light.

Big kids: 19 hours of daylight, since it’s 12 hours from 4:30 am to 4:30 pm, then another 7 hours.  Bonus: 75 inches.

And to find out the sunrise and sunset times for your town on any day of the year, check out http://www.sunrisesunset.com/USA/!

### Laura Overdeck

Laura Bilodeau Overdeck is founder and president of Bedtime Math Foundation. Her goal is to make math as playful for kids as it was for her when she was a child. Her mom had Laura baking before she could walk, and her dad had her using power tools at a very unsafe age, measuring lengths, widths and angles in the process. Armed with this early love of numbers, Laura went on to get a BA in astrophysics from Princeton University, and an MBA from the Wharton School of Business; she continues to star-gaze today. Laura’s other interests include her three lively children, chocolate, extreme vehicles, and Lego Mindstorms.