Physics Today
 
Follow us: Facebook    Twitter    rss    E-mail alert

text size Enlarge text Shrink text

print Printer-friendly format

write the editor Comment on this article

pdf pdf

Bookmark and Share

Letters

Galileo, Kepler share IYA anniversary

February 2010, page 9



Here’s a little postscript to the International Year of Astronomy 2009. Although it
 celebrated the 400th anniversary of the telescopic discoveries of Galileo, the
 IYA was the quadricentennial of another monumental event in the history of
 astronomy and physics—the publication of Johannes Kepler’s Astronomia Nova. In that work Kepler stated his first two laws of planetary motion: the
 ellipticity of planetary orbits, which finally broke the circular mindset of
 his predecessors, and the sweeping of equal areas in equal times (conservation
 of angular momentum). Surely his text deserves celebration as well, for it led
 directly to Newton’s law of universal gravitation later in that century.

Michael Lieber
University of Arkansas
Fayetteville