I am going to do something a bit different this week. On Friday I will be hosting the Science, Technology, Engineering and Math (STEM) Friday book meme here at Growing with Science. To celebrate, I am going to have a post with recently-published science books every day this week.

Our books today are What Do We Know About Stars & Galaxies? by John Farndon and Milky Way and Other Galaxies (The Solar System and Beyond) by Megan Kopp are excellent introductions to all the new discoveries that have been made about galaxies: how galaxies form and how they behave. (See Wrapped in Foil for a full review of the books.)

Illustration from NASA

How do scientists study objects in space? Modern astronomers use a variety of telescopes to capture information about the universe. Often the telescopes are part of orbiting satellites in space. Megan Kopp’s book, in particular, covers the technology that is used to study galaxies. She talks about the Hubble Telescope, the James Webb Telescope, the Spitzer Space Telescope, and the Alpha Magnetic Spectrometer-2, affectionately known as the AMS-2.

How do telescopes monitor galaxies? The telescopes capture light or some of other forms of radiant energy, such as radio waves, infrared, or microwaves. These forms of radiant energy are called electromagnetic radiation.

What is the electromagnetic spectrum? It shows range of frequencies of the different forms of electromagnetic radiation. At one end, radio waves have a low frequency (long wavelength) and at the other, gamma waves are high frequency (short wavelength).

(The electromagnetic spectrum from lowest energy/longest wavelength (at the top) to highest energy/shortest wavelength (at the bottom). (Credit: NASA’s Imagine the Universe))

This week we will start with an introductory activity to organize the information, plus discuss radio waves. Next week we’ll investigate more of the different forms of electromagnetic radiation in Part 2.


1. Create an electromagnetic spectrum wall chart.

Use a wall chart to record your observations about each type of radiation.


  • a roll of paper about five to six feet long (butcher’s paper works great)
  • colored markers
  • tape to fix the paper to the wall (painter’s tape won’t leave a mark)
  • yardstick (optional)
  • an example of the electromagnetic spectrum like the one above (search the internet for “electromagnetic spectrum images”)

Study the example of the electromagnetic spectrum. Write the names of the different types of radiation from left to right across the center of the paper in order of size of wavelength: Radio waves, microwaves, infrared, visible light, ultraviolet, x-rays, and gamma rays. Add information to the chart under each type as you learn more doing the activities.

2. What is a wave?

You may have read that light and its relatives travel in waves. What does that mean?

Think about physical waves, like the waves in the ocean or sound waves. Electromagnetic waves exhibit a similar motion.

See how you can vary the wave with different motions. Gather a jump rope or other heavy rope. Have two children hold each end to the rope tightly. Now have one move the rope up and down while the other stays still. Can you create a wave motion? What happens when you speed up or slow down? How about if you move your arm higher or less?

Now we will look at different types of electromagnetic radiation, starting at the radio waves, which have the largest wavelength and low energy, to gamma rays, which have the smallest wavelength and highest energy.

3. Radio waves

Have you ever wondered how radios work? How does electricity and sound waves become transmitted through the air via radio waves?

Currently the largest telescope to detect radio waves from space is the Arecibo Radio Telescope in Puerto Rico.

Studying the electromagnetic spectrum helps us understand more about astronomy, as well as other fields like communication and medicine and it is really too much for a single post. I will link to posts about microwaves, infrared, visible light, ultraviolet, x-rays and gamma rays as they are published.

Edit: Part 2 is now published.

Our books today:

Earth Space and Beyond: What Do We Know About Stars & Galaxies? by John Farndon

Hardcover: 48 pages
Publisher: Raintree
ISBN-10: 1406226289
ISBN-13: 978-1406226287

What Do We Know About Stars & Galaxies? Express version by John Farndon

Reading level: 3 (simpler version for younger children)
Library Binding: 48 pages
Publisher: Heinemann-Raintree (August 1, 2011)
ISBN-10: 1410941620
ISBN-13: 978-1410941626

Milky Way and Other Galaxies (The Solar System and Beyond) by Megan Kopp

Reading level: Ages 9-12
Paperback: 32 pages
Publisher: Capstone Press (August 1, 2011)
ISBN-10: 1429672277
ISBN-13: 978-1429672276

Disclosures: Books were supplied by the publisher for review purposes. Also, I am an affiliate for Amazon. If you click through the linked titles or ads and make a purchase, I will receive a small commission at no extra charge to you. Proceeds will be used to maintain this self-hosted blog.