Lesson 1: The Sun What would Earth be like without the sun? How would you describe the sun?

The sun is a star. What is the Sun? star A star is an object that produces its own energy, including heat and light.

stars The planets and the other objects in the solar system are not stars because they do not produce their own light.

The sun is the largest object in the solar system.

If the sun where a hollow ball, more than a million Earths could fit inside it.

However, if comparing the sun to other stars, it is just average in size.

The only reason the sun looks so much larger than the other stars that can be seen in the night sky, is because it is so much closer to Earth.

astronomers call this distance one astronomical unit The sun is 92,960,000 miles away from Earth. To make this distance easier, astronomers call this distance one astronomical unit. The next closest star to our solar system is 271,931 AUs away!

What is the sun? The sun is a star (an object that produces is own energy). The sun is the largest object in our solar system.

How does the sun produce its own energy? Albert Einstein discovered a relationship between mass and energy. He showed this relationship in a now-famous equation: E = MC 2

E = MC 2 E -> energy M -> mass C -> the speed of light (671 million mph) This formula shows that just a little bit of mass can be turned into a whole lot of energy.

The sun is mostly made up of the gas hydrogen. Hydrogen has very little mass. However, inside the Sun, the hydrogen particles smash together.

fusion This smashing together is called fusion. A little bit of mass is lost when H particles combine to make helium. According to Einstein’s equation, that little bit of mass is changed into energy. We see this energy as light and heat.

fusion So the process of fusion is how the sun produces energy.

How does the sun produce energy? The sun’s hydrogen atoms smash together and form helium (fusion) and some energy is released.

What are the parts of the sun? Scientists have divided the sun in layers.

Most of the energy the sun produces is formed in its core. At its core, the temperature is around million degrees Celsius.

The radiation layer moves the energy out from the core in every direction. It can take millions of years for energy to move out of this layer because it’s moving randomly around.

In the convection layer, gases move in circles, similar to air currents. Energy moves out of the layer in about a week.

The photosphere is the visible surface of the Sun. It is not solid, but a layer of gases. It’s obviously cooler here—only 10,346 degrees.

The chromosphere, or inner layer of the sun’s atmosphere, can be seen like a red circle around the sun.

The corona is the outermost layer of the sun’s atmosphere. It takes on different shapes depending on the changes in temperature.

Solar Flares Solar flares are bursts of heat and energy that stretch out from the corona into space. Sometimes, this energy can disrupts satellites, interfere with TV, radio and cell phone communication on Earth.

Solar flares are the causes of displays of different colored lights in the upper atmosphere. These lights are called aurora borealis, or northern lights.

They are most often seen in Alaska, Canada, and the north US.

They’re only seen in the southern US if the sun releases large amounts of energy.

Solar flares are also associated with sun spots. Sun spots, or dark spots on the sun, are sections of the sun that have a lower temperature than the surrounding areas.

Lesson Review 1. What is the largest object in our solar system? The sun 2. The sun is a star. What is a star? An object that produces its own energy (light and heat).

3. Why are the planets NOT stars? Planets do not produce their own energy (light and heat) 4. What two gases make up most of the Sun’s matter? Hydrogen and helium

5. How does the Sun produce energy? Hydrogen particles smash together and create helium and energy, which is called fusion. 6. How would the Earth be affected if the sun stopped producing energy? Without the sun’s energy, everything alive on Earth would die.

7. All of the following are part of our solar system EXCEPT A.the sun. B.Earth. C.the Moon. D.the stars. D. The stars The only star in our solar system is the sun!