The Sun
The Parts of the Sun
Like other stars, the Sun is simple in its composition. Stars are giant balls of hydrogen and helium gas held together by their own gravity. They are tremendously hot and have very high pressures. In the interactivity below, click on each of the spinning circles to learn more about the structure of the Sun. Click the player button to begin.
View a printable version of the interactivity.
Now that you have examined a model of the Sun, learn more about the Sun's different layers in the video The Anatomy of the Sun from eMediaVA℠. As you view the video, make note of how the scientists describe the composition of this important solar body.
Then, to learn more about the Sun's location, size, and temperature, view the NASA video Characteristics of the Sun from eMediaVA℠. As you view the video, make note of how the Sun compares to other stars, as well as to the Earth.
Solar Wind
You may already know that it takes around eight minutes for the light from the Sun to reach Earth's atmosphere. Did you know that gases from the Sun also travel towards the Earth, like a breeze? The proper term for this type of traveling radiation is solar wind. Solar winds are composed of low-density gases and can blow past Earth at 300 to 800 kilometers per second, taking 3 to 4 days to reach Earth from the Sun. Solar wind can impact Earth's atmosphere, causing beautiful light phenomena or interruptions to certain types of radio signals. Astronomers monitor solar activity to predict these interruptions.
Nuclear Fusion
As you already know, stars produce energy by nuclear fusion, and the Sun is no exception. But, what exactly is nuclear fusion? Nuclear fusion is a chemical reaction that occurs in the core of every star. A simple definition of the process is when lighter elements combine to create heavier elements. Since the most common element in the Sun is hydrogen, it is atoms of this element that fuse together to form atoms of helium. When fusion occurs, four hydrogen nuclei are fused together to make one helium nucleus. Helium has an atomic mass that is less than the four hydrogen nuclei combined. This leftover mass is converted into energy. Of course it is a very small amount of mass that that is converted into energy, so many reactions must occur simultaneously in the core of stars. These reactions cause the core of a star to be incredibly dense and hot. As the Sun converts its hydrogen into helium, it slowly loses mass over time. When a star runs out of hydrogen to fuel nuclear fusion, it begins to die. The Sun is approximately 5 billion years old, halfway through its lifespan of about 10 billion years.
Solar Activity
The surface of the Sun is very active. Even at a distance of 93 million miles away, this solar activity is important for astronomers to study because the Sun's radiation has an affect on Earth. In this presentation, you will learn about different types of solar activity, like auroras, sunspots and coronal mass ejections. Click the player button to begin.
View a printable version of the interactivity.
To learn more about how Earth is protected from the harsh solar activity of the Sun, view the video Earth's Magnetic Shield from eMediaVA℠. As you view the video, make note of what it is about the Earth that makes it protected from solar particles. Is this protection fail-safe?
Space Weather
Did you know that astronomers keep daily checks on the incoming solar radiation from the Sun? In a way, astronomers are documenting the space weather. The reason for keeping a close watch on the Sun is that the radiation traveling in that high energy plasma (solar wind) can really have a large impact on satellites and ground-based systems that rely on technology. Take a few minutes to explore the NOAA Space Weather Prediction Center website. Here, you will find the current space weather conditions.
While you are visiting this website, consider the following questions:
- Are there any current alerts?
- What is the speed of the solar wind?
- How many sunspots are visible during the solar cycle?
- Are either of the aurora visible?
- Have any storms rated on the NOAA scale?
The Sun Review
Now that you have explored various aspects of the Sun, review your knowledge in this non-graded activity. In this non-graded activity, review your knowledge of the Sun. Follow the directions provided with each question and click SUBMIT to check your responses. Click the player button to get started.