The Bedtime Scientist

A question

How do sea turtles find their way home?

A calm, true answer. Then, if the wondering keeps going, the whole episode.

The short answer

They can feel the Earth's magnetic field. Every stretch of coast has its own slightly different magnetic signature, and a loggerhead hatchling seems to learn the one it was born on before it ever leaves.

Decades later, after crossing an entire ocean, a female can return to nest on that same beach. Nobody taught her the route. She has been carrying it the whole time.

Go deeper tonight

Sea Turtles: The Map Inside Her

The full episode, in one calm voice, with nothing that startles.

The episode

Sea Turtles: The Map Inside Her

0:00 9:11
Sleep timer

Read the guide for this one in the morning.

This connects to

Finding the way

One idea turns up in many different nights. Follow one and the library starts to join up.