Nature Example
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The Swallow's Sun Compass
Credit: Wikimedia Commons. Click here for the license
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Credit: Wikimedia Commons. Click here for the license
You've probably seen these amazing little birds zipping through the sky in summer, with their pointy wings and forked tails. But swallows are actually super-tough travellers! They are tiny globetrotters, and their lives are completely ruled by the Earth's seasons (its orbit) and the Sun's daily path across the sky (the Earth's rotation).
How they use space:
They have a built-in "sat-nav"! Swallows use the Sun's apparent movement as a compass to navigate thousands of miles.
💡 Fun Facts
- Swallows are "chasing the summer"! They make an incredible 6,000-mile journey (migration) from the UK all the way to southern Africa every single autumn to escape the cold winter. When our spring arrives, they fly all the way back!
- The Sun isn't a simple compass because it moves across the sky (or appears to move, as the Earth rotates!). To use it, a swallow has an amazing internal clock. It "knows" what time it is, so it can look at the Sun's position and instantly calculate which way is south. It's like having a watch and a compass rolled into one!
- How do they know when it's time to leave? They sense the change in day length! In autumn, as the Earth orbits the Sun, our part of the world tilts away, and the days get shorter. This is the swallow's secret signal to start its long journey south.
- Why come back to the UK at all? Because our long summer days (when our part of Earth is tilted towards the Sun) mean there is a massive buffet of insects flying around, which is the perfect food for raising their hungry chicks.
- What about on cloudy days? Scientists believe that as well as their Sun compass, swallows can also sense the Earth's invisible magnetic field to keep them on the right track, just like a real compass!