How many stars do you see when you look up at the sky at night? Did you know there are over 300 billion stars in our galaxy? In our solar system alone, we have eight planets and five dwarf planets, but only one star that we know of. That star is the Sun.
The Sun is a star in the middle of our solar system – what scientists refer to as a heliocentric model. But centuries ago, scientists believed in a geocentric model – a model where the Earth is at the center of our solar system. How did scientists like Nicolaus Copernicus and Johannes Kepler figure out that the Sun is at the center of our solar system, and that the Earth spins on an axis while going around the Sun without the computers and scientific instruments we have today? They did this through observations.
These scientists put in a great amount of time and energy, and worked together so that they could share information that would lead them to answers to questions about the Earth, the Sun, and other planets and stars around us.
With patience, you can see what scientists saw back in the 1500s. With the warmer weather, it’s a great time to observe the night sky. And, who knows what a great science project this might turn into? Follow the instructions below, and make and record some scientific observations of your own.
What you need:
• Acetate (clear plastic sheets)
• White-out correction fluid
• Tracing paper (one sheet for every observation)
• Marker, pen, tape
• Compass or compass app
• Journal or notebook
Suggested: SkyView (free app)
What you do:
- Pick a location that offers a clear view of the stars above, and where you will be able to sit consistently at 15- to 60-minute intervals, over a period of three or more hours, every day for a week. Go out every night at the same times. (For example, if you go out on the hour at eight, nine, and ten, repeat those times throughout the week).
2. Use your compass to figure out what direction you are facing, and record that in your journal.
3. Once you have your location, hold your acetate up in the air, and use your white-out to make dots in all the spots where you see stars and planets. Try to map out a constellation and planets (because they are more recognizable) and you can see them move across the sky. You can use the recommended SkyView app or a galactic chart to help you identify stars, planets, and even satellites.
4. Take your sheet of acetate inside, and let the white-out on the acetate dry.
5. Once the white-out is dry, place a sheet of tracing paper over it and tape it on one side. With a marker, indicate the spots of the different stars and planets. If you can, try to label the constellations and planets.
6. Write down the time, date, and location of your observation.
7. Repeat this step for every observation.
8. Try to determine how the information you’ve recorded helped inform scientists about the Earth’s movement in our solar system.
Note: You can wipe off your acetate and reuse it or label each sheet and use a new sheet. Make sure you are always in the same spot facing the same direction, so you can see the stars and planets moving across the sky when you compare your tracing paper records.
Challenge: For an extra challenge, try figuring out where the stars will be a week from when you started, a month from when you started, and by the winter solstice. Do the stars seem to be traveling in a curved direction or a straight line? Do they move higher and lower in the sky? Do you think the same stars will be in the same spot at the same time next year?