Radio Astronomy is a branch of astronomy that uses radio telescopes to detect and amplify radio waves emitted by celestial objects. By monitoring both optical and audio signals from space we can gain a more complete picture of events occurring in space. This article is an introduction to radio astronomy.

What are radio waves?

Radio waves are a type of electromagnetic radiation with longer wavelengths than visible light. They are used to transmit data from radios, satellites and radar and are also used for telecommunications purposes. They are low-frequency electromagnetic radiation waves that travel through the air, invisible to the naked eye. Radio waves are detected by bouncing off satellites and then decoded into audible sounds by specialist equipment.

Whilst humans have used radio waves to communicate with each other, in Radio Astronomy we are interested in listening in to the radio waves emanating from space.

The history of Radio Astronomy

Radio waves were first detected between 1886 and 1889 by Heinrich Hertz but at the time he couldn’t see what use they would have in everyday life. In addition, Thomas Edison, Guglielmo, Marconi, and Nikola Tesla were all searching for radio waves in the late 19th and early 20th century. It wasn’t until 1931 when Karl Jansky, an American physicist and radio engineer first detected radio waves from space, but little was done to follow up on this discovery until after the Second World War.

How are radio waves detected?

From 1945 Bernard Lovell was able to show that radar echoes could be obtained from daytime meteor showers. Along with his research and university funding he was able to build the Lovell telescope, which was the largest steerable radio telescope in the world. The Lovell telescope remains at Jodrell Bank and remains a very productive means of gathering information. 

How does Radio Astronomy work?

Radio astronomers process the masses of information collected by a telescope converting the strings of numbers into sounds and images. Each number represents information from a specific point in space. Often, they have colours assigned to the numbers corresponding to the amount of information they represent. Astronomers then combine the colours to make an image, visualising the information to reveal some of the characteristics of objects in the Universe.

What is Radio Astronomy used for?

In much the same way that you tune a radio to the station you require, radio astronomers can tune their telescopes to pick up radio waves millions of light years from Earth. Using sophisticated computer programming, they can unravel radio signals from space to study the birth and death of stars, the formation of galaxies and the various kinds of matter in the Universe.

In its simplest form, a radio telescope has three basic components: –

• Antennas which point to the sky, to collect the radio waves.
• Receivers and amplifiers to boost the very weak radio signals to a measurable level.
• Recorders to keep a register of the signal.

Radio telescopes can be used both day and night, even if it’s cloudy, which can be very beneficial in the UK!

What has Radio Astronomy helped us to discover? 

Radio astronomy has changed the way we view the Universe and dramatically increased our knowledge of it, for example: –

• Astronomers trying to identify the source of interference in a radio antenna in the 1960’s discovered the Cosmic Microwave Background Radiation, the afterglow of the Big Bang.
• Cold clouds of gas found in interstellar space emit radio waves at distinct wavelengths. As Hydrogen is the most abundant element in the Universe and is common in all galaxies, radio astronomers use its characteristic emission to map out the structure of the galaxies.
• Radio astronomy has also detected many new types of objects including pulsars, the rapidly spinning remnants of supernova explosions that send out regular flashes of radio waves, much like the beam from a lighthouse. 

Everyday technologies based on Radio Astronomy

The science and engineering behind radio astronomy can also benefit our everyday lives.

For instance: –

• Wireless LAN technology, which was developed from our expertise in radio astronomy which led to ‘fast Wi-Fi’, which is now the way most of us access the internet.
• Pulsars offer potential as extremely accurate clocks and are possible alternatives to satellite-based global positioning systems (SAT NAV).
• Array telescopes are a group of several radio antennae many miles across that work together as a very large single antennae giving much better resolutions. The VLA (Very Large Array) in New Mexico is the largest example of an array telescope. These telescopes will hopefully advance our lives even further in the future with greater discoveries.

Radio Astronomy at Sherwood Observatory

At Sherwood Observatory we have a 50Mhz beacon transmitter. This Meteor Beacon transmits a circular polarised signal vertically upwards to illuminate the region of the sky where meteors typically burn up and create ionisation which is reflective to radio. Echoes from these ionisation trails are picked up by the receiver network hosted by partner organisations across the UK and can be used to detect, count and study meteor events over much of the UK. 

As well as detecting meteors we study solar activity using direct and indirect radio observations.

The Radio Astronomy Centre is open to the public on our open days/nights. Our radio astronomy technology is constantly recording activity for us to analyse and interpret. You can view live streams from the UK Meteor Beacon project here: https://ukmeteorbeacon.org/beaconclient/

Author – Stephen Binns