The subject of astronomy is so vast that there are countless great projects and experiments that can be used for science fairs and other classes. Younger kids have a natural affinity for astronomy. Whether it be learning about the moon or their place in the solar system, there are plenty of studies children can do for an excellent science project focused on space.
Astronomy Projects for Observing
Light Pollution - Pick a constellation in the sky to observe, such as Ursa Major (the Big Dipper). Observe the constellation from different locations, such as a city, the suburbs, and the countryside. Are stars visible in some locations and not others? Try observing in one location under different lighting situations, such as with the house lights and exterior lights on or off, or in view of the neighbor's garage light or farther from it. How does light pollution affect our view of the sky? What can be done to limit light pollution? Would a change in the type of light fixtures help to focus light away from peoples' eyes and the sky?
Moon Observing - One moon project is to have children observe the moon each night. How does it change? What happens to its shape and its location? Why does this occur? Is the moon always in the sky every night? Can they predict what the moon will look like the next night after a string of observations?
Crater Creator - How are craters formed on other planets? Mercury and our moon have many craters. Experiment in a pie pan filled with sand or other material what happens when a pebble is dropped into the sand. Try different surface textures and different size rocks. What about planets like Earth and Venus that have thick atmospheres? How would the outcome be different if the pebbles impacted an atmosphere before the surface?
Moon Phases - One project involving the moon is to demonstrate that children understand why the moon changes its "face". Use a lamp with a bare bulb to represent the sun. The kids can use their own head to represent Earth. Then use a ping pong ball to represent the moon. Have the moon circle Earth and see what parts of the moon (ping pong ball) are illuminated depending on the configuration of the Earth, Sun, and Moon.
Astrology Debunker - This one is for children who are old enough to read well. Get the astrology column in the daily newspaper and cut off the labels for each advice section. Label the back of each section: for example, Aquarius = 1, Aries = 2. Then enlist students to read the column and find the one that best described their day. Ask the student for their "sign" and see if it is the same as the column they picked. Do a large sample to determine if the astrology readings match real life.
Maybe you can come up with your own project for astronomy. Replicate the solar system and show why inner planets orbit faster than outer planets. Show how the seasons occur on Earth. The possibilities are endless!