Eratosthenes was a Greek philosopher, astronomer, mathematician and poet born in 274 BC in Cyrene in present-day Libya and died in 194 BC in Alexandria, Egypt. …

The Moon is the easiest astronomical object to observe. Simply raise your head on a clear night to see it (except during the new moon phases, when it is positioned between the Earth and the Sun). No need for an astronomical device, your eyes are enough. If you want to…