Sciency Words: Decametric Radio Emissions

Today’s post is part of a special series here on Planet Pailly called Sciency Words. Each week, we take a closer look at an interesting science or science-related term to help us expand our scientific vocabularies together. Today’s term is:


The decameter doesn’t get as much love as the meter or the kilometer, but it’s still a perfectly legitimate S.I. unit of measure. It equals ten meters.

In 1955, astronomers Bernard Burke and Kenneth Franklin detected radio emissions coming from the planet Jupiter, radio emissions with wavelengths long enough to be measured in decameters. Thus these emissions came to be known as the decametric radio emissions.

Surprisingly, the decametric radio emissions don’t radiate out into space in all directions. Instead, they shoot out like laser beams. Or perhaps I should compare them to searchlights. As a result, we can only detect them here on Earth if they happen to be aimed right at us.

Now here’s the part that I find really interesting. There are currently seven known sources for the decametric radio emissions, and they’re classified into two groups: Io-dependent and Io-independent.

The Io-independent sources require Jupiter’s magnetic field to align with Earth just so in order for us to hear them. And the Io-dependent sources? Well, they depend on Io, one of Jupiter’s moons. Jupiter’s magnetic field has to align with Earth, and Io has to be in the proper phase of its orbit.

I’m not sure why I think the decametric radio emissions would sound like dubstep. Click here, here, or here to find out what they actually sound like.

In next week’s edition of Sciency Words, we’ll take a closer look—a much closer look—at Io. It seems this humble little moon does more than adjust Jupiter’s radio emissions. Io wields enormous power and influence over the entire radiation environment surrounding Jupiter.

P.S.: Okay, on second thought, maybe we shouldn’t get too close to Io.

4 thoughts on “Sciency Words: Decametric Radio Emissions

    1. I’m only now beginning to appreciate Io’s importance. I have two more Io-related posts in the works. If Io keeps surprising me, there may end up being more.


  1. So what your telling us is Jupiter moon lo is providing all this radio laser power which humans can see and hear sometimes from earth, right? I guess this is where Spock is supposed to say – ionised gas – and Uhura – well its gotta have a tail pipe somewhere? hehe

    Liked by 1 person

    1. Well, Spock and Uhura would be pretty close to the truth on this one! My follow up to this post was on the Io plasma torus. That seems to be the connection here: ionized gas coming from Io’s volcanoes.


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