Ole Roemer Biography

Thatcher Svekis
Mr. Percival
Astronomy 0
12 Oct. 2007
Ole Roemer
In Arhus, Jutland, on September 25th, 1644, Ole Christensen Roemer was born into the world he would so intensively study for the majority of his life. Dying on September 23rd, 1710, two days before his sixty-sixth birthday, Roemer would best be remembered as the astronomer who determined convincingly that light had a definite speed.
Roemer was not born into a high class, as his father was a skipper and his mother the daughter of an alderman. As he lived in relative obscurity, not much is known about him until his emergence in 1662 at the age of eighteen. This was when he was immatriculated into the University of Copenhagen and served as an apprentice and pupil to Rasmus Bartholin. Fortunately for Roemer’s future in astronomy, Bartholin had been assigned the task of preparing Tyco Brahe’s observations for publication, so Roemer was given a great in-depth look at the particulars of astronomy. In 1671 he would assist astronomer Jean Picard in locating Brahe’s observatory, and would serve as a companion to Picard in Paris for nine years after 1672. This time was spent making observations at France’s royal observatory, teaching the Dauphin, and constructing the beautiful fountains at Versailles. It was also in this time that he would observe the moons of Jupiter. Unlike Galileo though it was not to prove heliocentrism, but instead to shed light on…light.
Roemer began tracking Jupiter’s nearest moon Io as it orbited the planet, and he observed naturally that it orbited in the same amount of time every time. Six months later, Roemer observed that Io emerged from the shadow fifteen minutes later than usual. Roemer took into account the movement of Earth compared to Jupiter, thus accounting for the delay. To lose these fifteen minutes, Roemer calculated that Earth had to move 192,500 miles per second. Was he right? Well he was within three percent, which is pretty good for more than three hundred years ago. From this information Roemer predicted when the fifteen minutes would be gained back, and was correct about that too. At the age of thirty-one, Roemer presented these findings to the Academy to set the precedent that light has a finite speed, and is not affected by relative movement.
He would be best remembered for this discovery about light, but would still have an eventful remainder of his life. He embarked on a scientific mission to England in 1679, meeting gravity-establisher Isaac Newton, Edmund Halley, and John Flamsteed. Upon his return to Denmark in 1681 he was appointed the professor of astronomy at the University of Copenhagen. He married the daughter of his mentor Bartholin, and as royal mathematician introduced Denmark’s first national system of weights and measures in 1683. In 1700 he convinced the king of Denmark to introduce the Gregorian calendar, which Tyco Brahe failed to do so a century earlier, and established a few navigation schools throughout Denmark. He would serve as Chief of Police in Copenhagen until he died, and was most remembered for firing the entire staff upon his promotion due to low morale. He introduced oil street lamps in Copenhagen and exhibited a sort of social reform by trying to limit the number of homeless in the city. Roemer passed away in Copenhagen in 1710 at the age of sixty-five, but was not forgotten in the city of his death. Though astronomy would remember him for establishing that light had a finite speed, Copenhagen would remember him as a hard-working citizen and proponent of social reform.

Works Cited
Leinhard, John H. "No. 682: the Speed of Light." The Engines of Our Ingenuity. University of Houston. 12 Oct. 2007 .
"Ole Roemer." LoveToKnow1911. 29 Aug. 2006. 12 Oct. 2007 .
The Biographical Encyclopedia of Astronomers.