Discovery of pluto

Did You Know…

…that ZEISS Helped Discover Pluto?


In the mid-19th century, irregularities in the orbit of the planet Neptune led astronomers to suspect that there could be a ninth planet. At first, the inaccurate orbital data made it difficult to know in which quadrant of the sky it would be found. Later on, time-delayed exposures of the night sky were compared using the naked eye, a time-consuming process.

The 1904 development at ZEISS of what was called the blink comparator proved to be the major turning point. It shows in rapid succession two images of the same part of the sky taken at different times. This helps makes the change in position of the more proximal celestial bodies stand out, thus simplifying the search considerably. At the Lowell Observatory on 18 February 1930, the young research assistant Clyde Tombaugh used this apparatus to compare two images on photographic plates that he had taken on 23 and 29 January. Lo and behold, in the space between Taurus and Gemini he found a tiny object: Pluto.

Today, Pluto is no longer classified as a planet. Because additional bodies have been discovered at the edges of our solar system, the International Astronomical Union decided in August 2006 to assign it to the newly defined class of dwarf planets. And now, after the discovery of slightly larger Eris in 2005, Pluto is in second place even in this category.

9 February 2010

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