I’ll have a Sporadic-E please Bob

You will see several mentions of Sporadic-E on this site, so I’ve taken a shot here at explaining the phenomenon in my own words. I hope you enjoy the tangent from the usual posts, but if you are already versed in solar physics feel free to skip along- wait maybe you won’t get that reference unless you read this bit… 🤔

Credit: The ESA/NASA Solar and Heliospheric Observatory (SOHO)

Sporadic E events- a phenomenon frequently observed in the early 90s as the increased frequency of the Sun’s coronal mass ejections created observable disturbances in the Earth’s ionosphere.

The phenomena occurs naturally every 11-year cycle, waxing and waning between the peaks- known as the solar maximum– during these periods, the most sunspots are produced.

Sunspots are a product of the complex interactions between the suns powerful magnetic fields and the fusion reactions occurring deep within the core of the sun. Magnetic fields twist and contort through the plasma as the sun rotates on its axis, eventually some of these powerful magnetic fields can no longer hold on to their couplings and break apart in violent and destructive solar flares, scattering the sun’s plasma deep into space. Sometimes, directly at Earth.

The difference between a solar maximum and a solar minimum.


Powerful magnetic interactions during solar flare events also cause magnetic disturbances that travel at the speed of light towards Earth. These are known as geomagnetic storms and can in the most extreme cases cause severe problems for the electrical grids that deliver power to our industry and homes, as well as damage satellites that operate out beyond the protection of our magnetic field.

Approximately three days after a geomagnetic storm, the sub-light-speed particles ejected from the sun arrive at Earth and hit the magnetic field, and if powerful enough can sometimes reach the upper ionosphere. These particles are extremely high-energy, if they were to reach the surface of Earth they would have a devastating and deadly effect on biological organisms.

The magnetic field of Earth is generated by the planet’s liquid core- much like a bicycle dynamo, the magnetic interaction though rotation of the different densities of liquid metal in the core produce strong magnetic fields that protrude out from the north and south poles, enveloping the Earth with a magnetic shield.

As the sun shines, it also emits solar radiation in the form of a constant stream of charged particles- this ambient bombardment is known as the solar wind.

Aurora Borealis as captured from the International Space Station

The solar wind speed increases dramatically during sunspot activity, putting greater pressure on Earth’s magnetic envelope. As the magnetic field interacts with the solar wind, particles billow around the envelope towards the poles- the weakest points of the magnetic field- where the charged particles interact with the oxygen and nitrogen gas in the upper atmosphere- this can be observed visually as the Aurora Borealis and Aurora Australis.

Sporadic-E is the name designated for the unpredictable property of the ionosphere when the solar wind travels deep and at high enough energy through the ionosphere that it causes a plasma to occur. This plasma is conductive, and therefore capable of reflecting radio frequency back to the ground.

This is how high frequency (HF) radio waves that would otherwise be absorbed by the ambient ionosphere propagate great distances beyond line of sight. Although the radio waves always travel in a straight line from the source, they can bounce off the sporadic plasma and back towards the ground. In combination with the ocean, this can sometimes happen multiple times before the radio wave is intercepted by a radio receiver. This is colloquially known as radio skip.

Other forms of radio propagation such as Tropospheric Ducting affect VHF and higher frequencies.

For the most part the F1 and F2 layers form from the separation of the radio-absorbing D layer at night when the solar wind reduces pressure on the magnetic field facing away from the sun, as Earth rotates from day to night- this allows shortwave to propagate further which is why distant radio stations can only be heard coming through in the evening hours.

Sporadic-E layers of the ionosphere are responsible for the majority of radio propagation phenomenon at upper-HF frequencies, such frequencies as the common CEPT and UK CB radio specification and the 10, 6 and 4 meter amateur radio band.

X My Pi!

Remastered with fully re-recorded material directly from a real Commodore Amiga, composed in AHX Tracker.

Have an Amiga and would like to try out AHX yourself? Grab the AHX User Manual Redux from GitHub. Dale over at dope.fish put the printable booklet PDF manual together with the help of numerous contributions (mine included!) making it a superb resource to pick up & print.

Many of these tunes exploit bugs (out of bounds parameters) to cause some glitch effects. Naturally, emulators/PC-playback routines didn’t anticipate this and summarily crashed to pieces when these were first released.

If you have a fairly up-to-date copy of XMPlay with the hivelytracker-ahx plugin, you should be golden to play the original source files, available here:

Hivelytracker

An updated version of AHX for high-end Amigas, supporting up to 16 channels of AHX synthesis- Hivelytracker. Compatible with AHX and has its own format (HVL) for advanced synthesis such as ring-modulation.

NASA OsirisREX: Asteroid Bennu

We have discovered the heart of Bennu, on the asteroid itself!

For visibility I have rotated and colourised it below 🙂

Boulder #1

The image was taken by the MapCam camera on NASA’s OSIRIS-REx spacecraft on April 19, from a distance of 2.2 miles (3.6 km). For scale, the largest boulder is 190 ft (58 m) wide, which is about the width of a soccer field.

When the image was taken, the spacecraft was over the southern hemisphere, pointing MapCam south.

Child of the Dogstar

I’ve always had a thing for rotating things that resemble the motion of cogs turning in the mind, windmills spinning in the breeze, space probes flying through space, gyrating for their time-delay integrated image systems…(like Juno).

So it took over 20 years to track down one of my favourire children’s TV series- eventually discovering some terrible quality rips from someone’s VHS on YouTube, excellent!

But where’s the official release? I did some research only to find out that the reason there had not been an official home VHS or DVD release was down to the copyrights “being stuck in litigation limbo” with NZTV for over 20 years!

So no VHS or DVD releases until the late 2000s.

One must understand: this TV program was aired ONCE in the UK in the 1980s- of those few Saturday mornings that I did get to watch TV, I accidentally stumbled upon the very first episode which was a blessing, and got immediately hooked. Sci-Fi kids TV was rare.

I’m no 3D designer, so I really have no idea what I am doing and that’s why I find it fun to do. Using a demo version of Shapr3D on my iPad Pro, I created a series of models.

Below are some of the stages of the model design as well as some clips of source material from which this device originates.

This isn’t my first replica built either- I did build a replica when I was a kid out of cardboard and electronics, but of course, no photographs and nothing survived!

Over the course of it’s airing, Saturday mornings were delightfully punctuated by this eerie and seemingly malevolent device’s wishes to draw enough energy by [no spoilers] to make contact with its home/owners- I highly recommend watching the mini-TV series “Children of the Dog Star”, just for the fact its great B-quality Sci-Fi. See what you come away with- try and understand what it would have been like for an impressionable 7 year old like me.

Please Hold

Better to live to leap another day.

This is about hope, good vibes, expectations & the often complicated reality of rocket launches.

Live recorded the interaction, while I was composing and producing the graphics for this while tweeting with the company CEO. Not only that but the cat brought a live mouse into the house at 2AM, let it loose and I had time to catch that too (its in the video, briefly). Bless.

Patiently waiting on a 2 hour delayed, then eventually scrubbed launch for a DeltaV rocket containing one of my beloved spacecraft (well that is what I’d like you to believe *ahem*).