Observatory History
The University of Virginia's Leander McCormick Observatory was founded in 1877
through a $68,000 gift from Leander J. McCormick. The large contribution was
made possible by the fortune made from the 1831 invention of the mechanical
reaper by Leander McCormick, his brother Cyrus and their father Robert on their
farm near Steele's Tavern, VA. The gift was first offered to Washington
College, but was declined by the college's president, Robert E. Lee, partly on
the grounds that continuing support of the observatory would be difficult to
obtain. A letter to this effect from Lee to Joseph Henry, the first Secretary
of the Smithsonian Institution, can be seen in the observatory display area.
The Observatory was completed and opened in 1885, and the telescope was the first major scientific facility at the University of Virginia. For several years the 26¼-inch refracting telescope was the largest in the country and second largest in the world. Although later surpassed in size, the McCormick lens is still regarded as the most perfect large lens ever produced.
In 1914, under the energetic leadership of S. A. Mitchell, second director of McCormick Observatory and member of the National Academy of Sciences, the Observatory began an extensive program photographically measuring trigonometric parallaxes of nearby stars. Trigonometric parallax determines the distance to stars by comparing photographs of stars taken through a telescope six months apart.
In those six months, the Earth has traveled halfway around the sun and is now 186 million miles from the spot where the first photo was taken. If there is a nearby star in the region photographed, it will appear to have moved with respect to background stars when you compare photographs. The movement of even the closest stars is small, however, and can only be measured by carefully photographing the same region for years to eliminate any systematic errors.
You can try a similar experiment yourself if you hold your finger about a foot away from your face and then look at it with first one eye and then the other. Your finger seems to move with respect to the background because your eyes are a few centimeters apart.
The 2300 parallaxes determined at McCormick Observatory have been a very important contribution to astronomy. Only one other observatory has published a comparable number of accurate parallaxes.
The University's Department of Astronomy began collaboration with the Australian National University's Mount Stromlo Observatory, outside Canberra, Australia, in 1976 to extend its own research of stellar distance measurement to include the southern skies not visible from Charlottesville. The Mount Stromlo 26-inch telescope is much like the one here at the McCormick Observatory and was used for more than 20 years by astronomers from UVa.
Now, however, the Australian part of the program operates from a 40-inch reflecting telescope at Siding Spring Observatory outside Coonabarabran, Australia. This telescope uses a sensitive electronic detector instead of photographic film to measure star distance. The program carried out is similar to that underway at UVa.'s own 40-inch telescope located on Fan Mountain, near Covesville, VA.
At least one observer from the University of Virginia is resident in Australia year-round.
If your would like to learn amore about astronomy, please visit our website: http://www.astro.virginia.edu
