Johannes Hevelius Essay

Rion Koball

Mr. Percival

D.E. Astronomy

15 October, 2010

Johannes Hevelius

            Hevelius was a very accomplished Polish astronomer. He was so well known in fact, that a king and a queen visited him at his home to look at his home-made observatory. One reason his observatory was so great was that he had created a telescope with a 150 ft. focal length, by himself. He published many works, and was even considered the founder of lunar topography. Aside from being an astronomer, he was the town’s brewer and councilor. He was such a successful brewer that he ran the Brewer’s Guild for 12 years. He was a very well-rounded man and experienced a combination of careers in his lifetime.

            Johannes Hevelius’ observatory was a true masterpiece, spanning across three rooftops. His main instrument was his150 ft focal length telescope that he made simply with wood and wire. This was the single longest tubed telescope invented before aerial telescopes made their appearance.

            Hevelius had many visitors, all well-known in their own right. His observatory was visited in 1660 by the Polish Queen Maria Gonzaga, and in 1678 by the Polish King John III Sobieski. In 1679 he was visited by Edmund Halley, who had been instructed by Robert Hooke and John Flamsteed to convince Hevlius to use the telescope to make astronomical measurements. Hevelius then proved to Halley, in comparing data, that he could make more accurate or just as accurate measurements with his naked eye as Halley could with a telescope. He made the majority of his extremely accurate measurements by using the quadrant and alidade system; this made him the last major astronomer to not use a telescope for taking measurements. It is amazing that he still had good enough eyesight to make these measurements after the copious amount of time he spent staring at the sun observing sunspots.

            Johannes spent four whole years of his life dedicated to mapping the surface of the moon. Johannes’ major work was Selenographia, sive Lunae descriptio. This book was a collection of all of his observations, and his most successful work. He outlined in the book how his work was unique from Galileo’s, and that Galileo’s research felt like something was missing. One of Hevelius’ greatest pieces was a map of the topography of the moon. He is also credited with discovering the Moon’s libration in longitude (the effect of its eccentric orbit around the Earth). His work was considered so strong that it survived as one of the bases of information about the Moon for over a century. Some of his names for certain features of the moon still survive today.

            He also made other contributions to astronomy. He invented and created the constellation Scutum. It was originally published in one of his books, which was mostly printed in his own home, and engraved by Hevelius himself. He discovered four comets that moved in a parabolic path, which led to the thesis that they revolved around the Sun.

            Johannes may not have as well-known a name as Galileo, but he made a lot of major contributions to astronomy that still survive to this day. He was a pioneer to the study of Lunar topography, and was quite the handyman in creating observing tools. He was a very well rounded individual who had great success as a brewer and an astronomer. Johannes Hevelius’ naked eye measurements showed just how great an astronomer he really was.