Discovery of the Planet Neptune–September 23, 1846

On this day in 1846, German astronomer Johann Galle pointed his telescope into the sky in search of an as-yet-unidentified celestial object that was suspected of disturbing the orbit of Uranus. Researchers in several countries--including astronomers John Couch Adams, James Challis, and George Airy in England; and French mathemetician Urbain Le Verrier--were trying to predict and describe the object and its orbit. They were unsuccessful in directly locating the object themselves. But Le Verrier enlisted the help of Galle, an astronomer at the Berlin Observatory, and shared his predictions and work with him. With Le Verrier's calculations and a bit of luck, opens a new window, Galle spotted the object in question: a newly identified planet that would be called Neptune.

Neptune is the eighth and outermost planet in our solar system. With a 16-hour day and a roughly 165-year orbit around the sun, this ice giant is dark, very cold, and exceptionally windy. The sunlight that reaches Neptune is approximately 1/900th of the light that reaches Earth. Its average temperature, opens a new window is about -392 degrees Fahrenheit, and 1200mph winds blow across the planet. Talk about inhospitable! Fourteen identified moons orbit around Neptune, and several faint rings surround the planet. In 1989, the Voyager 2 spacecraft flew past Neptune, the first and (to date) only spacecraft to have done so.

The St. Tammany Parish Library has resources that provide more information about Neptune, as well as about the rest of our solar system and the wide universe beyond. Check some out today!

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Discovery of the Planet Neptune--September 23, 1846

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Looking for items about Neptune, our solar system, or astronomy in general? The St. Tammany Parish Library has lots to offer! Here's a list of just some of the items in our collection. If you need more information about borrowing any of these or other items, please contact a St. Tammany Parish Library reference librarian.



























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