Scientists have known for decades that many animals use the Earth's magnetic field for navigation. It's less clear how they do it. A new study suggests earthworms may be a good way to figure it out.

Scientists have known for decades that some animals use the Earth's magnetic field to help them navigate, kind of like an internal GPS. How they do it, though, remains unclear. NPR's Nate Rott reports ...

Scientists have known for decades that some animals use the Earth's magnetic field to help them navigate. Think of it as an internal GPS. But how it all works remains unclear. NPR's Nate Rott reports ...