# Who was the first scientist to successfully measure the speed of light using observations of Jupiter’s moon Io? with Answer - General Knowledge MCQs | TestPrep

> Solved MCQ: Who was the first scientist to successfully measure the speed of light using observations of Jupiter’s moon Io? Correct Answer: C. Ole Rømer. Verified answer explanation for FPSC, PPSC, MDCAT, NTS, and CSS competitive exam preparation.

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# Who was the first scientist to successfully measure the speed of light using observations of Jupiter’s moon Io?

Direct Answer & Quick Reference

The correct option is **C. Ole Rømer**.

In 1676, Ole Rømer, a Danish astronomer, was the first to successfully measure the speed of light by observing the apparent changes in the timing of Jupiter’s moon Io as Earth move...

A. Galileo Galilei

B. Isaac Newton

C. Ole Rømer **(Correct Answer)**

D. Albert Einstein

✨ Explain with AI

Verified Key: C. Ole Rømer
Solved by 5,562+ students

**Detailed Explanation & Reference:**

In 1676, Ole Rømer, a Danish astronomer, was the first to successfully measure the speed of light by observing the apparent changes in the timing of Jupiter’s moon Io as Earth moved closer to or farther from Jupiter.

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