How to Use Your FM Radio to Detect Meteors

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Updated November 19, 2011

Get Started   Meteor Showers  Equipment  Pick FM Station  How to Observe

You can use your FM radio to detect meteors as they enter the earth's atmosphere. As the meteor burns up on entry, atmospheric gases are ionized creating conditions that will reflect line of sight radio waves over the horizon from distant radio stations where they normally won't travel. If you are tuned to an FM radio station over the horizon from your home, and you hear music or voices, a meteor has probably passed between you and the radio station. Click this link to find sample audio files.

Please note: The information on this page is written with reference to locations in Alberta, Canada due to the mandate of this site as a public education project of the Edmonton Centre of the Royal Astronomical Society of Canada and the Dept. of Physics at the University of Alberta. However, most of what you see here applies to other locations around the globe.

Here's how to get started

  1. Check the Meteor Showers table for the dates of upcoming meteor showers. Pick a shower you want to observe.
  2. See What You Need to make sure you have the equipment required.
  3. Select an appropriate FM radio station.
  4. Make your observations.
  5. Look at your observations to produce data.

Meteor Showers

While meteors are constantly falling into the atmosphere, there are times each year when the number of meteors is noticeably higher. As the earth travels in its orbit around the sun, it passes through the paths of a number of comets and other space debris that also orbit the sun. These are called meteor showers

These showers are of particular interest to both amateur optical and amateur radio astronomers because they are predictable events to plan observing sessions around. Both optical and radio astronomers count the number of meteors they detect and compare notes with others observing in different locations. This provides useful information about changes in the nature of the shower stream. Follow this link for a list of Meteor Showers.

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More on how meteor showers work.

Equipment

You will need a good FM radio, an antenna, a method of recording your observation (optional), and a way of showing your data. Depending on how involved you want to get, you can also add a pre-amplifier and other recording equipment.

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Picking an FM Radio Station

When choosing an FM station to use for observing there are several steps you must take to select one that will work.

  1. Tune your radio from the lowest setting to the highest making a note of the frequency of each station that your radio can pick up. 

  2. For example, say there are 5 stations with frequencies of 88.9, 99.5, 101.1, 103.7, and 107.1. You must choose an FM radio station that does not broadcast on any of those frequencies.

  3. For best results, you need to choose a radio station that is about 1300 km (800 mi) away. This distance usually gives the longest duration signal. But you can also detect signals reflected off meteors from stations between 200 km (400 mi) and 2100 km (1300 mi) possibly even closer or farther away. Take a provincial or state road map and with a compass, draw three circles one at 200 km, a second at 1300 km and a third at 2100 km.

  4. Look in the FM station chart for a radio station that is between the smallest and largest circles. Make sure the station transmits on a frequency different from the ones that you can receive on your FM radio at home. If you can't find a suitable station in the table, bookmark this site and go to http://radiostation.com to find one. Look for stations with the highest power possible. 100 Kilowatts is a good figure. Please note that this website only lists radio stations within reach of the US border so stations in central and northern Alberta will not appear in your search.

  5. Note the compass bearing from your location. This will be important for pointing your antenna in relation to meteor shower streams.

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How to Observe

Connect the receiver to the antenna. Connect your data logging equipment to the earphone jack of the receiver. Start your software. Start the receiver. And away you go. These are the basic steps required. More detail on how to do each step is described on other pages on this website. See the Site Map for an overview of what is available.

It is better to observe overnight when human activity is at a low ebb. Also, the number of meteors observable increases at around 6 a.m. when the leading edge of the earth travels into the stream of sporadic or shower meteors. These meteors tend to enter the atmosphere at a greater speed because of the Earth's velocity through space of 28.8 km per sec. This higher energy translates into higher levels of ionization. As a result of these two factors, many radio meteor observers conduct their observations between midnight and 7 a.m.

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Copyright 1999-2012 by Sky Scan, Edmonton, Alberta, Canada. 

We gratefully acknowledge the financial support of the 

Edmonton Centre of the Royal Astronomical Society of Canada, Department of Physics (University of Alberta)

and the

Natural Sciences and Engineering Research Council of Canada

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