Lyceum B - Astronomy - Week 17 - The Sun
- Apr 3, 2022
- 3 min read
Updated: Apr 5, 2022
The gases in the Sun's core are under tremendous pressure from the layers above the core. Gasses under pressure become hot(25 million ° Fahrenheit)
Hydrogen nuclei join together in a process called nuclear fusion and this creates energy. This process creates lethal radioactive gamma rays and x-rays, but as these rays take a million years passing up through the overlying gas layers it becomes safer light and heat.
In the upper layers of the Sun, the energy circles in "convection currents". Once breaking through to the surface, it only takes 8 minutes for those light rays to reach the earth.
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From How the Universe Works:
Nuclear fusion works by bonding together the centers, or nuclei, of the Sun's hydrogen atoms. This complex reaction turns four hydrogen nuclei (protons) into one nucleus of helium. A helium nuclei is only 99.3 percent as heavy as four individual hydrogen nuclei, so the extra 0.7 percent is turned into our energy. Every second, over 4 million tons of the Sun are converted into energy.
The chain reaction happens like this:
Hydrogen protons fuse to form deuterium, which combines with more protons to form helium-3, which combines with another helium-3 to form helium-4.
The hydrogen protons go on to form new reactions. Energy is released in the form of heat and light.
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The sun is made up of five main layers.
The core is where the Sun's energy is formed as gamma and x-rays. The radiation passes to the radiative zone, where it loses some of its energy. The next layer is the convective zone, where the energy swirls back and forth beneath the surface.
It then moves through the photosphere and out into space through the Sun's lower atmosphere, the chromosphere.
The Sun Layers:
One way to investigate what is happening inside the Sun is to study its vibrations. The Sun is so large that each vibration is about 5 minutes.
The way that the Sun vibrates gives clues to its density, pressure, and viscosity.
We can use a glass of water to examine how this happens.
You need four identical glasses (wine glasses work well for this experiment). Pour an equal amount of water into three of the glasses until they are all 3/4ths full. Pour oil into the fourth glass to the same level.
Have another person stand facing away from the glasses so they rely only on their sense of hearing to distinguish if there is any difference in the vibration/sounds.
Mix up the order of the glasses. Then tap each glass lightly with a metal spoon while the person listens carefully to the resulting ringing sound. Can they tell which glass contains oil? Why do you think oil sound different than water?
This same thing is how scientists can tell what the density, etc. inside the Sun just from the vibrations it gives off.
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Convection Currents
Heat can travel by radiation, convection and conduction.
Radiation happens near the Sun's core while convection happens nearer the surface.
Convection is the transmission of heat by currents of gas or liquid. - How the Universe Works
To watch this happen in water, heat up water that you have put glitter into. The motion of the glitter shows the swirling convection currents happening in the water. The glitters rises with the hot water where it becomes cooler than the water below it that is now exposed to the direct heat. As the water beneath heats up and rises, it pushes the glitter outward to the sides, where it cools further and falls to the bottom to begin the cycle again.
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Corona:
A corona is an aura of plasma that surrounds the Sun and other stars. The Sun's corona extends millions of kilometers into outer space and is most easily seen during a total solar eclipse.
Auroras:
The top of the corona is continuously boiling off into space, in a raging gale of hot gases that sweeps out through the Solar System. As this solar wind passes the Earth, some of its particles descend into our atmosphere and lights up the air molecules in the colorful display of the auroras: the Northern and Southern Lights.
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Videos:
Star Systems and Types of Galaxies - Professor Dave Explains - 12:49 min
The Gravity of the Situation: Crash Course Astronomy #7 - 10:04 min
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