Ole RoemerOle Roemer

The Great DaneThe Great Dane

Roemer’s Humble BeginningsRoemer’s Humble Beginnings Born September 25, 1644 Born September 25, 1644

in Aarhus, Denmarkin Aarhus, Denmark Graduated from the Graduated from the

Aarhus Cathedral school Aarhus Cathedral school in 1662.in 1662.

Studied Mathematics and Studied Mathematics and Astronomy at University of Astronomy at University of Copenhagen Copenhagen

Moved to Paris when Moved to Paris when hired by Louis XIV to tutor hired by Louis XIV to tutor the prince.the prince.

Became a professor of Became a professor of Mathematics at the Mathematics at the University of Copenhagen University of Copenhagen in 1681. in 1681.

Romer’s Enemy: DescartesRomer’s Enemy: Descartes Measured the speed of light using the orbit of Measured the speed of light using the orbit of

Jupiter’s moon, Io.Jupiter’s moon, Io. Roemer’s discovery of finite C caused an uproar Roemer’s discovery of finite C caused an uproar

within the scientific community.within the scientific community. Descartes argued that light travels at an infinite Descartes argued that light travels at an infinite

rate. Descartes used a fancy diatribe to argue rate. Descartes used a fancy diatribe to argue why Roemer was wrong.why Roemer was wrong.

Descartes blunder??Descartes blunder??

Other ContributionsOther Contributions

Improved thermometer Improved thermometer accuracy. Advised accuracy. Advised Fahrenheit on his Fahrenheit on his temperature scales.temperature scales.

Developed the “Transit Developed the “Transit Instrument” to better Instrument” to better determine stellar determine stellar positions.positions.

And…And…

Finally…Finally… Professor of MathematicsProfessor of Mathematics Astronomer RoyalAstronomer Royal Master of the MintMaster of the Mint Purveyor of the Royal HarborsPurveyor of the Royal Harbors Inspector of Naval ArchitectureInspector of Naval Architecture Advisor on Pyrotechnics and Advisor on Pyrotechnics and

BallisticsBallistics Commissioner of HighwaysCommissioner of Highways Privy Council MemberPrivy Council Member First Magistrate (Chief Justice of First Magistrate (Chief Justice of

the Supreme Court)the Supreme Court) Chief Tax AssessorChief Tax Assessor Mayor of CopenhagenMayor of Copenhagen Prefect of PolicePrefect of Police SenatorSenator Head of the State Council.Head of the State Council.

““Roemer was too modest to Roemer was too modest to demand for himself any glory or demand for himself any glory or praise from his contemporaries; he praise from his contemporaries; he was too busy to be able to devote was too busy to be able to devote any of his time to the spreading of any of his time to the spreading of his ideas…Roemer, considered by his ideas…Roemer, considered by his contemporary scientists to be his contemporary scientists to be one of the leading figures of his one of the leading figures of his age, is today known generally only age, is today known generally only because of his discovery of ‘mora because of his discovery of ‘mora luminis’ and for the first luminis’ and for the first determination of the velocity of determination of the velocity of light.”light.”

-Bernard Cohen -Bernard Cohen (biographer)(biographer)