Labels:text | font | screenshot | paper | document OCR: THE ANCIENT GREEK ASTRONOMER Hipparchus (fl. 146 BC-127 BC) described the 20 brightest stars he could see as being "of the first magnitude," while the dimmest were "of the sixth magnitude." Those in the middle were given intermediate values. After the invention of the telescope, much dimmer stars could be seen, and, as telescopic power improved, great differences in brightness between stars of the first magnitude could be discerned. During the 18th century, the ratio between magnitudes was fixed at roughly 2.5 (2.51 18865 to be exact). This means that a star of a given magnitude is 2.5 times brighter than a star one magnitude dimmer. Hipparchus's system of describing the faintest stars visible to the naked eye as being of the sixth magnitude was retained, and you need an optical aid to see ...
