bild

Jerome de Lalande (1732-1807), French astronomer. Joseph Jerome Le Francois de Lalande trained as a lawyer, but also took a keen interest in astronomy. In 1751 he was sent to Berlin, Germany, to make observations of the Moon. Coupled with Nicolas de Lacaille's observations in South Africa at the same time, the parallax of the Moon was determined, and thus the distance of the Moon from the Earth. Parallax is the apparent shift in an object's position against a distant background when viewed from different places along a baseline. This effect can be reproduced by observing a nearby object with first one eye, then the other. (KEYSTONE/SCIENCE PHOTO LIBRARY/LIBRARY OF CONGRESS)