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How do scientists study objects far out in space? Modern astronomers use a variety of telescopes to capture information about the universe. Some of the telescopes are part of orbiting satellites outside the Earth's atmosphere; others are right here on Earth. These telescopes monitor light and/or its relatives, that is, light and other forms of radiation in the electromagnetic spectrum.

For example, radar and radio waves were used to investigate the recent asteroid that passed by the Earth.

To help understand how all this works let's explore the different types of radiation found in the electromagnetic spectrum. We split the activities into two posts because it is rather long. In Part 1 we started an electromagnetic spectrum wall chart, examined waves/wavelengths, and radio waves. Now let's find out more.

Part 2 Electromagnetic spectrum activities:

1. Microwaves

Because of microwave ovens, microwaves have become a household word. But what are microwaves and how do they work?

Microwaves are a form of electromagnetic radiation with wavelengths shorter than radio waves. They are used for all sorts of things, including remote sensing of weather for forecasting, as well as for monitoring space. Some forms are also used for communications.

In the microwave oven, substances containing water molecules absorb microwave energy and heat up.

This simple experiment from Steve Spangler is sure to get kids excited about microwaves.

Physics in the Microwave at Physics Central explains more and has ideas for "expanding" this experiment.

2. Infrared

We can't see infrared radiation with our eyes, but we can sometimes feel it is as heat. Certain snakes, called pit vipers, have organs on their heads that can detect infrared radiation (as a way to find their prey in the dark).

We can see infrared radiation using special cameras. Check out this online infrared photo album Click on "start" in the upper right hand corner to see real infrared photographs. If you click on the special magnifying lens and then move your mouse over the image, you'll see the same photograph in visible light. Look at the footprints. Where did they go in the visible light view?

If you have a Macintosh computer, you can fake an infrared photograph using the program Photo Booth. See if you can figure out how the program achieves this effect.

For more about infrared radiation, see:

(Image from NASA)

3. Visible Light


  • prism or glass of water

Take it outside on a sunny day and create rainbows by separating white light into its component colors. (See related post for more information and activities).

If you don't have a prism, Catch The Waves has a color spectrum interactive you can try online.

Demonstration that light waves are a form of energy:

A radiometer can be used to show that light is a form of energy. Place the radiometer in a sunny window and watch the blades/panels inside spin. Energy is the ability to do work, in this case moving the blades.

You can also convert light energy to heat energy by concentrating it with a magnifying lens. Have you ever burned a piece of paper with just sunlight and a magnifying lens? (Only with adult supervision.)

4. Ultraviolet (UV)

Ultraviolet radiation has a slightly shorter wavelength than visible light. Humans can't see ultraviolet light, but many other animals can, including honey bees and butterflies.

Many flowers have spots we can not see in visible light, but that show under ultraviolet light. Scientists call these spots and patterns "nectar guides" because they are thought to attract bees and other pollinators to the flower.

(Photograph is from Wikimedia Commons.)

Exploring ultraviolet:

a. Obtain or borrow an "black light" (available in many hardware and home supply stores). Black lights produce a type of UV light. Materials, such as florescent posters, glow under a black light. Try out the activities in this glowing chemistry post.

Some items that glow under a black light:

  • Did you know that ripe bananas glow blue under certain ultraviolet lights?
  • Scorpions glow when you shine a black light on them in the dark.
  • Certain minerals also glow under UV.

b. Gather some ultraviolet-sensitive beads (see below for one source) that change colors when expose to ultraviolet radiation. Find out whether you have to be in direct sunlight to be exposed to ultraviolet radiation. (We found that there was enough reflected UV in some shady places to color the beads.)

Saturn's Rings in ultraviolet light (Image from NASA)

5. X-rays

Have you ever had an x-ray taken, for example at a dentist's office or if you had a broken bone? X-rays are a form of electromagnetic radiation with a very short wavelength.

X-rays are considered to be "ionizing radiation," which means its energy levels are high enough that when it strikes a molecule it can remove an electron, thus forming an ion. Because of this property, exposure to X-rays should be limited.

6. Gamma rays

Certain gamma rays have the highest level of energy of all the forms of electromagnetic radiation, as well as the shortest wavelength. Here on earth gamma rays are only produced by lightning, radioactive decay of certain radioactive elements, and nuclear explosions. In space they are produced by high-energy events such as supernovas.

Gamma rays are harmful and helpful because they are used to treat certain cancers and to kill bacteria in food.

Light and its relatives in the electromagnetic spectrum have a lot of uses, including investigating space. Have you used any forms of electromagnetic radiation today? Leave a comment and let us know which ones.

Uv Beads are available through science, educational, and toy outlets.

LEDwholesalers 395 nM 51 UV Ultraviolet LED flashlight Blacklight 3 AA, 7202UV395

(If you purchase an item at Amazon through these links, I receive a small commission that is used to offset the costs of maintaining this website.)

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.