Rømer conversion (ºRø)

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Wordwide use:

This scale was widely used in Europe during the 18th century, particularly in Denmark, Germany, and the Netherlands. It was even adopted as the official temperature scale in Denmark for a period of time.

However, the Rømer scale gradually fell out of favor as more accurate and standardized temperature scales were developed, such as the Celsius and Fahrenheit scales. These scales provided greater precision and were more universally accepted, leading to the decline of the Rømer scale's usage.

Today, the Rømer scale is primarily of historical interest and is not commonly used in scientific or everyday applications. However, it remains an important part of the history of temperature measurement and serves as a reminder of the progress made in understanding and quantifying temperature.


The Rømer is a unit of temperature named after the Danish astronomer Ole Rømer. It was first introduced in the late 17th century as a way to measure temperature using the freezing and boiling points of water. The Rømer scale is based on the concept that water freezes at 7.5 degrees Rømer and boils at 60 degrees Rømer, with the scale divided into 60 equal parts.

To convert temperatures from Rømer to Celsius, you can use the formula: Celsius = (Rømer - 7.5) * 40/21. Similarly, to convert temperatures from Rømer to Fahrenheit, you can use the formula: Fahrenheit = (Rømer - 7.5) * 24/7 + 32. While the Rømer scale may not be commonly used today, understanding its definition and conversion formulas can provide insights into the historical development of temperature measurement.


The Rømer scale, also known as the Rømer temperature scale, was developed by Danish astronomer Ole Rømer in the late 17th century. Rømer was studying the motion of Jupiter's moon, Io, and noticed that the timing of its eclipses seemed to vary depending on the distance between Earth and Jupiter. He hypothesized that this variation was due to the time it took for light to travel from Jupiter to Earth.

To test his theory, Rømer conducted a series of experiments using lanterns and assistants positioned at different distances. He observed that as the distance increased, the time it took for the light to reach the observer also increased. Based on these observations, Rømer concluded that light had a finite speed and calculated it to be approximately 220,000 kilometers per second.

Rømer then applied his findings to the measurement of temperature. He developed a scale where the freezing point of water was set at 7.5 degrees and the boiling point at 60 degrees. This scale became known as the Rømer scale and was widely used in Europe for over a century before being replaced by the Celsius scale.

Common references:

Freezing point of water = 7.5ºRø

Boiling point of water = 60ºRø

Usage context:

One of the main reasons the Rømer scale was used in scientific and astronomical contexts was its relevance to the study of celestial bodies. During this era, astronomers were particularly interested in measuring the temperature of celestial objects such as stars and planets. The Rømer scale provided a convenient and consistent way to express these temperatures, allowing for easier comparison and analysis of astronomical data.

The Rømer scale was also used in scientific experiments and laboratory settings. It provided a useful alternative to other temperature scales of the time, such as the Fahrenheit and Celsius scales. Scientists and researchers could use the Rømer scale to measure and record temperatures in their experiments, facilitating the sharing and replication of scientific findings.

However, with the development of more accurate and standardized temperature scales, such as the Celsius and Kelvin scales, the usage of the Rømer scale gradually declined. Today, it is mainly of historical interest and is not commonly used in scientific or everyday contexts.


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