Sun

The Sun is a medium-sized star at the center of our solar system.  Scientists think that it is about halfway through it's 10 billion life cycle, so it has 5 billion years to go!  It has a couple of layers:

The first and innermost layer is the core, where nuclear fusion happens.  Nuclear fusion combines the elements hydrogen and helium to create solar energy, such as heat and sunlight.

The next layer is the radiation zone.  Particles of light carry the energy made in the core to the next layer, the convection zone.  The convection zone is the outermost layer of the Sun.  Gases in this layer rise and sink, cool and heat up, like convection currents in the Earth's mantle.

The Sun does not have a period of revolution, since all stars are stationary, but it does have a period of rotation which is 27 days.  The Sun makes up 99.8% of the solar system's mass.  Now I will talk about the layers of the Sun's atmosphere.

The first or innermost layer of the Sun's atmosphere is the photosphere.  It is the only layer of the Sun that is visible to the naked eye.  Since photo means light, it is the "light sphere".  It is so bright that it blocks out the other layers of the atmosphere.

The second layer of the Sun's atmosphere is the Chromosphere.  Since chromo means color this is the color sphere.  You can only see this layer during a solar eclipse.  It is like a red or orange line.

The last layer of the Sun's atmosphere is the corona.  This layer is so faint that it can only be seen during a total solar eclipse.  The gases from this layer reach really far into space and are called solar  wind.  Sometimes solar wind enters the Earth's atmosphere at the north and south poles and causes aurorae.  In the north pole it is called aurora borealis, and in the south pole it is aurora australis.

Now we will talk about some of the Sun's features.  Sunspots are areas of gas that are cooler than the gases around them, so they look darker.  They are always found in groups.

Another feature is prominence.  Prominence is a loop of gas connecting a group of sunspots.  Prominences can suddenly connect and form an eruption or explosion called a solar flare.  Solar flares can reach for hundreds of miles into space.  This is a picture of prominence.