Seeing Stars with Radio Waves?

What are radio waves?

They have the longest wavelengths and are found in the electromagnetic spectrum.  We can’t see them, so radio telescopes are used to detect them.  Check out the diagram below and compare how long it is!

What’s an electromagnetic spectrum?

It’s a series of waves arranged together like notes on a piano keyboard to form a scale. What does it mean?

• The 'low notes' have a low frequency and a long wavelength. 

• The 'high notes' have a high frequency and a short wavelength. 

The rainbow colours that we see are visible light waves and they are located in this spectrum.  Each light has a different wavelength.  

In case you didn’t know, all electromagnetic waves can cross a vacuum and travels at the speed of light!

It is designed to receive radio waves from space and it has 3 components:

a. Antennas

• To collect incoming radio waves. Most antennas are parabolic dishes that reflect the radio waves to a receiver (check out your TV satellite dish). Antennas can also be other shapes. 

b. Receiver and amplifier

• To boost the very weak radio signal to a measurable level. 

c. Recorder 

• To keep a record of the signal in a computer memory disk as astronomers use sophisticated software to process and analyse the data.

What can we do with a radio telescope?

Radio telescopes are always pointed towards the sky to observe planets, comets, giant clouds of gas and dust, stars and galaxies. Astronomers can learn about their composition, structure and motion by studying the radio waves originating from these sources. 

Since radio waves are longer than optical waves, radio telescopes are made differently than the telescopes used for visible light. Radio telescopes must be physically larger than optical telescopes in order to make images of comparable resolution. 

To get clearer (higher resolution) radio images, several smaller telescopes or receiving dishes are combined into an array. Together these dishes act as one large telescope whose resolution is set by the maximum size of the area.

Shared by
Azni Zainal Abidin
Learning Specialist, Petrosains