The Science of... Summer

What would you do with a full day of sunlight?

To mark the return of the summer, we are back with our Lit Lab blog series, 'the Science of…' Check back each week for a new blog in the series!

In case you didn’t know, the Lit Lab’s mission is a simple one: to help adults reconnect with science, and have a great time doing it. And this summer we are moving to a rooftop lab!

Through our events, we bring 18+ guests together for explosive science experiments mixed with social drinking, interactive competitions, and games.

Through our blog and community, we’re extending membership of our Littee Committee to share behind-the-scenes, experiments you can try at home, blogs, and news to help you reconnect with science wherever you are.

The Summer Solstice

Every June, something quietly spectacular happens in the sky. The Sun reaches its highest point in the sky at noon, casting the shortest shadows and gifting us with the longest day of the year. This moment is known as the summer solstice, and while it can be enjoyed in the park with friends, or having a few tipples in a rooftop bar, it’s actually an astronomical event rooted in the tilt of our planet.

It's all about the tilt

Earth is titled. The 23.5 degree angle tilt of Earth, relative to its orbit of the sun, is what gives us the seasons and the summer solstice. The fact Earth is tilted means that throughout the year different parts of the planet receive varying amounts of sunlight.

This year, on 21st June, the Northern hemisphere was tilted directly towards the sun, giving us the summer solstice - the day when the Sun appears to stand still at its northernmost point before reversing direction.

And just like lots of things in nature, the tilt of Earth does not stay the same, and can become less or more tilted, which affects the severity of the seasons. More of a tilt means more dramatic seasons, with hotter summers and colder winters. Whilst less of a tilt means cooler summers and milder winters.

The experience

On the summer solstice in London, you would have experienced the Sun rising around 4:43 AM and not setting until 9:22 PM. That’s over 16 hours of daylight! But the winner is definitely a city in Norway called Tromso where the sun does not set, giving them 24 hours of daylight! And if you were outside at noon, your shadow will have been the shortest it will be all year, due to the sun being at its highest point in the sky.

After experiencing the longest day of the year, the days then slowly begin to shorten - a reminder that nature is always in motion.

Solstice Science Fun facts

Want to impress your friends and family at your next summer gathering with some solstice science? Read on:

• The word solstice comes from the Latin solstitium, meaning “Sun stands still.”

• The solstice doesn’t always fall on 21st June, it can occur between 20th and 22nd. This is because Earth is getting slower - it takes nearly a quarter of a day longer to complete its orbit each year than our calendar accounts for, you can almost think of it as Earth's aging process. This is also why we add a leap day every four years, to keep the calendar aligned with Earth's orbit.

• The solstice marks the longest day, but it’s not usually the hottest. That’s because Earth’s land and oceans take time to warm up, a phenomenon known as seasonal lag.

  
  

Understanding the solstice isn’t just about astronomy, it’s a reminder that we’re part of a vast, dynamic system. That the Sun, 93 million miles away, still shapes our days, our seasons, and our lives.

---

Sources

Greshko, M. (2025). What is the summer solstice? Here’s what you need to know. Science. Available at: https://www.nationalgeographic.com/science/article/summer-solstice .

NASA (2000). Milutin Milankovitch. Nasa.gov. Available at: https://earthobservatory.nasa.gov/features/Milankovitch/milankovitch_2.php.