October 2017 Discover

OUT THERE

POWERED BY ASTRONOMY MAGAZINE

October 2017^ DISCOVER^63

STAR LIGHT, STAR BRIGHT

Just how bright is that star? Scientists measure them by magnitude, a system in which the brightest stars get the lowest numbers. This

confusing method was conceived by Greek astronomer Hipparchus (illustrated above) more than 2,000 years ago and remains in use around

the world today. Read more on page 64, and find out why some small galaxies are turning cannibal, beginning on page 70.  ERNIE MASTROIANNI;

ENGRAVING BY NORTH WIND PICTURE ARCHIVES/ALAMY STOCK PHOTO