What can we learn by studying stars?

Every day there is light during the day followed by darkness at night.  If the day is sunny, you might notice shadows.  Day, night, and shadows are caused by light from the Sun and the movement of Earth.  The solar system includes the Sun, the planets, and other objects that travel around it.  The Sun gives off energy (heat and light) that moves out in all directions through space. 

You see the Sun in the sky on a sunny day.  The Sun is in the sky on cloudy days too.  The Sun is a star – a giant ball of hot, glowing gases (called plasma).  If you think of a plate that is almost round, the Sun would be in its center.  Earth would be between the center and the plate’s edge.  The Sun is the star closest to Earth.    

The Sun is the main source of light and energy for Earth.  The Sun looks larger and brighter than stars you see at night because it is a lot closer to Earth.  The other stars in the sky look small because they are so far away.  All stars give off heat and light, but all but the Sun are so far away we cannot feel their heat.    

Earth is very small compared to the Sun.  Like the Sun, Earth is shaped like a ball.  Unlike the Sun, Earth does not glow or make its own light.  The half of Earth’s curved surface facing the Sun is lit by sunlight.  The half of Earth’s surface facing away from the Sun is not lit by sunlight and is dark. 

Stars can be different in size and appearance; some are smaller, some are larger, and some appear brighter than others.  Telescopes help us see stars that our unaided eyes cannot see.  Telescopes show us that stars can be different - different sizes, colors, brightness and distance from Earth.