Essential Facts about the Sun
- The Sun, the largest object in our solar system, accounts for more than 99.8% of its total mass. Jupiter holds the remaining 1.2% of the mass.
- Various mythologies have personified the Sun. For Greeks, it was Helios, for Ancient Indians, it was Surya, and for Romans, it was Sol.
- At present, the Sun is about 70% hydrogen and 28% helium by mass. The remaining less than 2% consists of other elements. This composition changes over time as the Sun's core converts hydrogen to helium.
- The Sun's outer layers exhibit differential rotation, rotating once every 25.4 days at the equator and up to 36 days near the poles. This is due to the Sun not being a solid body like Earth.
- The Sun's core, approximately the inner 25% of its radius, has extreme conditions. The temperature is 15.6 million Kelvin, and the pressure is 250 billion atmospheres. The Sun’s density at the core is more than 150 times that of water.
- The Sun's photosphere, the surface, has a temperature of about 5800 K. Sunspots, “cool” regions with a temperature of only 3800 K, appear dark only in comparison to the surrounding regions. Sunspots can be very large, up to 50,000 km in diameter, and are caused by complex interactions with the Sun’s magnetic field.
- The Sun’s magnetic field is strong and complex. Its magnetosphere, also known as the heliosphere, extends well beyond Pluto.
- The Sun’s output and sunspot activity are not entirely constant. The latter half of the 17th century saw a period of very low sunspot activity known as the Maunder Minimum, which coincided with an unusually cold period in northern Europe, sometimes referred to as the Little Ice Age.
- The Sun is about 4.5 billion years old and has used up about half of the hydrogen in its core. It will continue to radiate “peacefully” for another 5 billion years or so, but will eventually run out of hydrogen fuel. This will lead to radical changes, resulting in the total destruction of the Earth.
Characteristics of the Sun
Find the various characteristics of the Sun in the tables below:
Orbital Characteristics
| Mean distance from Earth |
1 au ≈ 1.496×108 km
8 min 19 s at light speed |
| Visual brightness (V) |
-26.74 |
| Absolute magnitude |
4.83 |
| Spectral classification (G) |
G2V |
| Metallicity |
Z = 0.0122 |
| Angular Size |
31.6–32.7 minutes of arc |
Now, let's look at the physical characteristics of the Sun:
Physical Characteristics
| Equatorial radius |
695,700 km
696,342 km
109 × Earth |
| Equatorial circumference |
4.379×106 km
109 × Earth |
| Flattening |
9×10-6 |
| Volume |
1.41×1018 km3
1,300,000 × Earth |
| Mass |
1.9884×1030 kg
333,000 × Earth |
| Average Density |
1.408 g/cm3
0.255 × Earth |
| Center Density |
162.2 g/cm3
12.4 × Earth |
| Temperature |
Center (modeled): 1.57×107 K
Photosphere (effective): 5,772 K
Corona: ≈ 5×106 K |
A Brief Overview of the Sun's Corona
The Sun’s corona, its outermost part, is usually hidden by the bright light of the Sun’s surface, making it difficult to see without using special instruments. However, it can be viewed during a total solar eclipse. The corona is made up of plasma (hot ionized gas) and has a temperature of approximately two million kelvins and an extremely low density. The Sun’s magnetic field continually affects the corona, causing its size and shape to vary.
Questions on the Sun
The Sun is primarily composed of hydrogen (about 70%) and helium (about 28%), with the remaining 1.5% consisting of carbon, nitrogen and oxygen. The remaining 0.5% is made up of small amounts of many other elements such as neon, iron, silicon, magnesium and sulfur.
The Sun is estimated to be about 4.5 billion years old, about halfway through its life cycle, according to scientists.
The Sun is a ball of gas and plasma, with hydrogen making up about 91% of the gas. This hydrogen is converted into energy in the Sun’s core, which then moves outward through the interior layers, into the Sun’s atmosphere, and is released into the solar system as heat and light.
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