The Sun

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     When you think of the Sun, what do you think of? Do you think of the ball of light that make days perfect to play in, or do you think of the middle of our Solar System? I would bet that many of us don't really know that much about the Sun. The Sun is a mysterious object, and we know very little about it.

     What we do know, is that the Sun is a giant star. It is classified as a medium large yellow dwarf star. It is 4.5 billion years old and is made of hydrogen, helium, calcium, sodium, magnesium, and iron. It is 93 million miles away from the Earth. The Sun is very different than the Earth. First of all, the Sun is much hotter. The heat and radiation from the Sun is what makes our planet hot. Imagine the hottest day that you have experienced, (Around 100 degrees Fahrenheit), and multiply the heat by 99. The surface temperature of the Sun is about 9900°F. All the planets in our solar system rotate around the Sun. If you think a building is heavy to lift, well, the mass of the Sun is 1.98892 × 10³⁰ kilograms. Now that's heavy! The Suns gravity is about 28 times that on Earth. That means if you weigh 100 pounds on Earth then you would weigh 2800 pounds on the Sun. The Sun is 900,000 miles across. If it were hollow it could fit a 100 Earths inside it. That's around 99.8% of the whole Solar System's weight!

You may be wondering about what kind of materials make up the Sun. With its kind of weight, you would probably think that it’s made of really heavy metal. You’re wrong! It’s actually made up of the 70% of hydrogen, 28% helium, the gas that makes balloons float, and less than 2% is metal. Also, as more time passes, the hydrogen in the Sun will slowly become helium. The Sun converts seven hundred million tons of hydrogen  into 695 million tons of helium and five million tons of gamma rays every second! These gamma rays become the sunlight that we see from our own planet.

Structure:

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     The Core is the hottest part of the Sun. It extends from the center to about 0.2 solar radii. It is 13,600,000°K. This is where nuclear fusion takes place, converting hydrogen into helium. 3.4×10³⁸ hydrogen atoms are converted into helium atoms every second. The Sun's core has a very low rate of energy output, about 0.3W/m³/s, which less power than what a candle generates. It takes 10,000-170,000 years for a photon (radiation) to travel to the surface and go into space.

      The next area is the Radiation Zone. It extends from 0.2 to about 0.7 solar radii. In here, the solar material is dense enough to transfer the immense heat of the core outwards. The heat travels in the form of radiation. It is passed from atom to atom as it slowly makes its way to surface.

     The Convection Zone is next. In this area the solar plasma is not hot or dense enough to transfer the heat by conduction. Therefore heat is transferred by convection. Thermal columns carry heat to the the surface and as it cools plunges back to the bottom of the Convection Zone. These columns are usually shaped as hexagonal prisms.

     The Photosphere is the surface of the Sun. This is the part of the Sun that is visible to us. After the photosphere the energy produced by the Sun is free to escape into space. It is tens to hundreds of kilometers thick. The temperature here is 5,780°K.

     The atmosphere of the Sun is compromised of five main zones. the temperature minimum, the chromosphere, the transition region, the corona, and the heliosphere.  The innermost zone is the temperature minimum. It starts about 500 meters above the surface. The temperature here is about 4000°K. Above this is the chromosphere. It is about 100,000°K near the top and is about 2,500 meters thick. On top of this is the transition region. Here the temperature ranges from 100,000°K to 1,000,000°K. Next is the corona. The temperature here is between 1.5-2 million degrees Kelvin. Finally comes the heliosphere. It is the outermost region extending past the orbit of Pluto.

     Sunspots are areas of the Sun that have intense magnetic activity. The magnetism around these areas cause the convective columns to stop making the temperature cooler causing it to be darker compared to the rest of the surface. They usually appear in pairs with opposite magnetic polarity.