In astronomy, what does retrograde mean? And what connection does it have to astrology? We explain how planets move across ...

On the side of the coin on the left is a man's head facing right, with long curly tendrils of hair held in place with an ornamental headband, small dots surround the border. The other side of the coin ...

Claudius Ptolemy was born around AD 85, and spent most of his long life in Alexandria. He was a noted geographer, and constructed a map of Europe whose shapes agree remarkably well with the ...