10 Interesting Facts About Our Sun

The Sun
Image Credit: Melissa van Niekerk

In many ancient cultures, the sun was seen as a symbol of divine power and revered as a deity. We now know that the Sun is just another star like the ones seen in the night sky, but this does not make our nearest stellar neighbor any less awe-inspiring. Here are 10 top facts about the Sun for you to enjoy!

1. The Sun is Classified as a Yellow Dwarf

The Sun is classified as a G-type yellow dwarf (G2V), which is a little misleading as stars in this sequence can vary in color from yellow for cooler stars, to white for the hotter ones. In actual fact, our sun is just under halfway through its almost 10 billion year stellar life cycle and is white in color.

On Earth, we see the Sun as either yellow, orange, or red as these are the colors of the longer wavelength lights which make it through our atmosphere. This process is why the sky appears blue, as shorter wavelength lights, such as blue and violet, are absorbed by the atmosphere, thus giving it its bluish hue.

2. It is the Biggest Object in the Solar System

The Sun is the hottest, biggest, most massive object in the solar system, and contains more than 99.8% of the solar system’s mass, with Jupiter accounting for more than 80% of the remaining 0.2%. To put the word “biggest” into some sort of perspective, here are some figures showing how the Earth matches up to our nearest star:

  • Circumference: Sun 2,713,406 miles (4,366,813 km), Earth 24,901 miles (40,075 km).
  • Diameter: Sun 900,000 miles (1,392,684 km ), Earth 7,917 miles (12,742 km).
  • Radius: Sun 432,450 miles (695,500 km), Earth 3,959 miles (6,371 km).
  • Weight: Sun 333,000 times heavier than the Earth.
  • Volume: Sun more than 1.142 quintillion cubic kilometers, meaning it would hold about 1.3 million Earths.

3. The Sun’s Gravity keeps the Solar System together

We also know that the Sun’s immense gravitational field keeps the planets from flying off into space, with its gravitational pull at the equator 274 m/s2, or 28 times more powerful than the Earth. To put this in perspective, if you weighed 90 kg on Earth, you would weigh 2,520 kg on the Sun.

4. The Sun is almost Spherical

Given the immense size and volume of the Sun, it is remarkable that an object almost 1.4 million km (900,000 miles) across has polar and equatorial diameters which differ by only 10 km (6 miles). This fact makes the Sun the closest thing to a perfect sphere yet discovered in nature, and if the sun was shrunk to the size of a beach ball, the difference between its widest and narrowest diameters would be less than the width of a human hair.

5. The Sun generates Winds and Flares

The Sun generates roughly 386 billion billion mega Watts of energy through nuclear synthesis, as it converts hydrogen into helium. This energy travels outward from the core and is continuously absorbed and re-emitted at progressively lower energy levels and temperatures until it emerges from the surface, where some of it becomes visible as optical light. Some of the Sun’s energy is then radiated as heat, but it also powers a stream of energetic particles that is perhaps better known as the solar wind.

This wind blasts through the solar system at a velocity of 450 km/sec (280 m/sec) and it has destroyed dozens of satellites and caused havoc with radio and TV reception on Earth. It has also caused major power blackouts because it causes short circuits in power grids when the energetic particles penetrate the insulation of high-tension cables and switchgear. Sometimes, the Sun will blast off hundreds of millions of tons of material in the form of solar flares that are associated with Sun-spot activity, which seem to “explode” when magnetic field lines in the Sun break through the surface.

6. The Sun has a simple Chemical Composition

The Sun consists of only a few elements, of which hydrogen is predominant at around 72%, and helium at about 26%, with the other elements accounting for progressively smaller amounts, such as oxygen, carbon, neon, nitrogen, magnesium, iron, and silicon. Here are some more figures, comparing 1 million hydrogen atoms in the Sun to various elements:

  • 98,000 helium atoms.
  • 850 oxygen atoms.
  • 360 carbon atoms.
  • 120 neon atoms.
  • 110 nitrogen atoms.
  • 40 magnesium atoms.
  • 35 iron atoms.
  • 35 silicon atoms.

7. Sun’s Magnetic Field up to 3,000 times stronger than Earth’s

Although the Sun’s magnetic field is only about twice as strong as Earth’s overall, the differential rotation of the Sun concentrates the field in some places, where it can be as much as 3,000 times as strong as on Earth. Magnetic concentrations manifest as “Sunspots”, and only occur up to about 45 degrees north and south of the solar equator, because it is in this region that the differences in the rotation rates of different part of the Sun is greatest.

Greater disruption in the Sun’s magnetic field cause solar flares that can extend hundreds of thousands of miles above the surface. Less violent eruptions are known as “coronal mass ejections,” during which incredible amounts of matter is blasted off the Sun’s surface, up to about 20 billion tons of matter in a single event.

8. The Sun has a reversible Magnetic Field

Sunspots can number from zero to about 250+ during each 11-year period (solar cycle), after which the sun’s polar magnetic field reverses its polarity. This cycle, however, is not constant and it varies with overall magnetic activity. From about 1645 to 1715, for instance, there was little to no sunspot activity, and this period became known as “The Little Ice Age.”

During this time, normally ‘ice-free’ rivers froze over, and fields at lower altitude levels remained ice-bound right through the year, causing widespread famine over much of America and Europe. However, a causal connection between Sunspot activity and climatic conditions on earth has yet to be established or disproved.

9. The Sun has an Internal Structure

While the Sun’s core takes up the inner 25% of its structure and accounts for 2% of the Sun’s total volume, this region contains close to 50% of the Sun’s total mass, given the fact that it is 15 times dense as lead. The next most massive area is the radiative zone that extends from the outer edge of the core to roughly 70% of the way to the surface. This region accounts for 48% of the Sun’s total mass, and 32% of its total volume. Photons created in the core get bounced around in the radiative zone so often that on average, it takes them about a million years to reach the surface.

10. The Sun’s Corona is Hotter than its Surface

Common sense dictates that the further one moves away from a heat source, the cooler the ambient temperature should be, but the opposite is happening on the Sun. In other words, the further one moves away, the hotter it gets. This was first noticed as far back as 1939, but recent research seems to have solved the mystery.

Surprisingly, the Sun’s corona is 10 million Kelvin (18 million degrees Fahrenheit)  compared to only 5,778 K (about 10,0000 F) on the surface or photosphere. This is the result of solar flares that are too tiny to be detected individually, and as Jim Klimchuk, who is a solar scientist at NASA’s Goddard Space Flight Center in Greenbelt, Maryland, explains:

“The explosions are called nanoflares because they have one-billionth the energy of a regular flare. Despite being tiny by solar standards, each packs the wallop of a 10 megaton hydrogen bomb. Millions of them are going off every second across the Sun, and collectively they heat the corona.” Problem solved.

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