Aristotle and other ancient Greek scholars suggested that the Earth was round based on different observations. For example, departing ships appear smaller and seem to sink into the horizon, as would be the case when sailing across a round surface like a ball. However, the Earth was proposed to be round before Christopher Columbus, a navigator, sailed the blue ocean.

Isaac Newton came up with a different proposal of the Earth not being perfectly round. According to the Newtonian theory, Earth is flat on the North and South pole, then has a swelling or bulge across the equator – an ellipsoid. Although his suggestion was different from that of other researchers, Newton was correct since the distance between the Earth’s center and sea level is greater at the equator than the North and South poles.

After researching the auroral phenomena, Anders began making trips to Italy, Germany, and France. It was in Paris where he met a French Mathematician – Pierre Louis Maupertuis. During their time together, the French mathematician planned an expedition to take measurements of the north meridian. Influenced by his educational background, Celsius joined Pierre on his voyage on Dec 3 -1736. He frequently visited London during the time to obtain the needed equipment for the task.

The expedition aimed to disprove the Cartesian proposal of the Earth being spherical and conversely approve Newtonian theory that stated the Earth was an ellipsoid. As a skilled astronomer, Celsius played a significant role in measuring the north meridian, supporting or verifying Isaac Newton’s theory that Earth is an ellipsoid.