In 1835, Charles Darwin, on his historic voyage, visited Chile, where he met a German naturalist called Renous. Renous had recently been jailed for heresy (of all things). He was raising caterpillars to study butterflies, but the good people of San Fernando did not know that caterpillars turn into butterflies. Surely, turning one animal into another was witchcraft!
We now know what a caterpillar is, but even so, more than 180 years later, we still know little about butterflies. Each year, Monarch butterflies make a voyage far more impressive than Darwin’s, flying over 7500 km (4700 miles) from the eastern U.S. to Mexico and back – that’s like a human being circling the globe 2325 times!  Their migration routes were a total mystery till 1975! And it took another 40 years to discover how they find directions.
Amazingly, Monarchs time-compensate the sun’s location to navigate correctly (meaning that they know that the sun is in the east in the morning, and in the west in the evening). But how do they navigate when the sky is overcast? The answer: They can see guiding lines in the sky! Continue reading