New Hampshire Astronomical SocietyMarch 17th in Astronomy and Space Science
 | 1846 | Prussian astronomer Fredrich Bessel dies. He is the first to use the concept of parallax to measure the distance to nearby stars. By charting a star's position at two times, six months apart, he uses the diameter of the Earth's orbit, about 310 million km (186 million miles), as his baseline. His first measurement, on the star 61 Cygni yields a distance of 11 light years, very close to today's accepted value of 11.1. |
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