The Sun is the parent star of the Solar System around which the bodies of the planetary system gravitate, which also includes the Earth . Its mass alone represents 99.9% of the mass of the entire Solar System, but do you know exactly what the diameter of the Sun is? We reveal it to you below, in addition to explaining how it is calculated.
What is the diameter of the Sun and how is it calculated
The Sun is essentially composed of hydrogen (74% of its mass), helium (25% of its mass) and other elements present only in small percentages.
As it is not a perfect sphere , but is slightly flattened at the poles, it is not possible to define an absolute value for the diameter of the Sun ; Instead, it is possible to define what is the minimum diameter, the maximum diameter and the mean diameter of the sun.
It is clear that the minimum radius is polar while the maximum radius is equatorial.
As we will see, the difference between the minimum diameter and the maximum diameter is very small, confirming that the Sun is an almost perfect sphere.
Minimum diameter, maximum diameter and mean diameter of the sun
The values of the diameters , measured in meters (m) and in kilometers (km) are the following:
- Minimum diameter = 13.909108 m = 1390900 km
- Maximum diameter = 13.91 108 m = 1,391,000 km
- Mean diameter = 13.9094108 m = 1390940 km
These values, if we express them in AU (astronomical units), are the following:
- Minimum diameter = 9.29759222 10-3 AU
- Maximum diameter = 9.29826068 10-3 AU
- Mean diameter = 9.29785962 10-3 AU
The diameter of the Sun is enormous compared to the diameters of the planets in the Solar System.
In fact, if we compare what is the diameter of the Sun with the diameter of some other planets in the Solar System, we can say that it is approximately the following:
- 285 times larger than the diameter of Mercury , which is the smallest planet in the Solar System;
- 109 times larger than the diameter of the Earth;
- 10 times larger than the diameter of Jupiter , which corresponds to the largest planet in the Solar System.
The way that solar diameter is measured is by first taking measurements of a regular diameter and then translating them to linear diameter measurements . The angular diameter of the Sun, or more precisely of the photosphere, can be measured using telescopes especially during total solar eclipses or by timing Mercury when it is in transit in front of the Sun. The first series of measurements was taken in the early 1700’s by Jean Picard in Paris France.
