Well, after nearly eight years, this Bad Astronomy Newsletter — the BAN — has reached quite the kilometerstone^*: the 1000^th issue^**.

I’m a big agog over this. A thousand issues! That’s nuts. The first issue came out in April, 2016, and at the time I wrote two per week, a free one on Monday and one for paid subscribers on Thursdays. I added a second paid weekly issue on Tuesdays starting in September, 2022, because there was just too much astronomy to cover, even with writing my column for SYFY at the time, too.

I still face that problem, to be honest. I write a column for Scientific American every Friday (and one is edited to go into the print issue every month, too), and I still find myself with way more stuff to write than I have a place for. I must have ten BAN issues worth of stuff sitting in a drafts folder at any given time. I keep thinking I could add another issue per week, but I can’t figure out the business model for it (charge more? Have a different tier level so people can subscribe for different amounts to get different issues per week? Nothing seems to work, though if you have a suggestion, feel free to leave them in the comments below, which I’ve opened up to everyone today, both free and premium subbies.]

Anyway, a thousand. That’s a lot! Each issue has roughly 1,000 words, though usually closer to 1,100 – 1,200. So either way, that’s over a million words in this newsletter total^***.

A popular science book usually has about 80,000 words in it. That means this newsletter is the equivalent of over a dozen (maybe even a baker’s dozen) books! That’s a lot of science.

And I’ve been happy, ecstatic even, to bring all that science (and other stuff, too) to you — roughly 21,000 of you at the moment, both free and paid. And I thank each and every one of you. Truly! Otherwise I’d be shouting into a vacuum, and I already have social media for that.

As we all have, I’ve been through a lot over the past six years. Various political setbacks, weird illnesses (including one very nearly serious one), moving across country, and more. I’m glad so many of y’all have kept with me all this time.

I love astronomy. LOVE it. Science too, but astronomy especially, and it is beyond wonderful that so many of you do too. Thanks for being here, and I hope you stick around for many years more.

Ad astra per legere! Probably! I never took Latin!

^* As I’ve noted before, I love the metric system both scientifically and mathematically, but prosaically it leaves something to be desired. At least in this case “kilometerstone” is prefix-appropriate.

^** Or, as they would have written in ancient Rome, the M^th issue.

^*** So far!

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It’s long been theorized that dust devils and dust storms on Mars might produce electrical discharge effects, similar to lightning. The idea is that small grains of basaltic rock covering the planet can get picked up in the winds, rub against each other, and exchange electric charges, some getting more negative and some more positive. This is called the triboelectric effect (the same effect that lets balloons stick to walls after you rub them on your hair) The grains then get separated in the wind, and, if enough of these oppositely charged particles accumulate, they can reach a high enough voltage to discharge, creating a flow of electrons that breaks the imbalance.

This is essentially lightning. The scale is much smaller, but the physics is roughly the same.

And now, it looks like it’s finally been detected! The Perseverance rover recorded the sounds of wind from both dust devils and storms, and heard the distinctive crackle of electrical discharge, followed shortly by an acoustic boom, the sound wave from the superheated air [link to journal paper].

The crackle is from the flow of electricity affecting the electronics in the rover’s microphone, and has the characteristic shape expected from a sudden release of electrical energy. The scientists detected 55 such events over two Martian years (about four Earth years).

Here’s some audio from one dust devil passing near the rover. The crackle is at the 9 second mark or so:

The energy involved with these events is pretty small, ranging from 0.1 – 150 nanojoules. A joule is already a small unit of energy, but compare that to a terrestrial lightning bolt that can discharge about a billion joules! So these Martian versions are far smaller, by a factor of about a quadrillion. They’re similar to the shock you get if you touch a metal doorknob after walking across a carpet, and in fact the discharge length (essentially the length of the spark) they determined for most of these events was about a centimeter, so it’s way more like getting zapped by static electricity than lightning. 

They did find a bigger discharge of about 40 millijoules (a million times stronger) that they think happened when the rover itself built up a static charge after being pelted by basalt grains, and discharging it into the ground. That discharge length was 40 centimeters, which sounds about right.

This finding has implications for studying the atmosphere and dust on the Red Planet. For example, a dust grain with a charge will be more easily picked up by a charged wind than a neutral one, affecting how dust moves and where it winds up. It also affects the chemistry of the surface, and could be a hazard for electronic equipment (both in robotic and human explorers) so it needs to be investigated further.

I’ll add that in my book Under Alien Skies I have a chapter describing what it would be like to walk around on Mars, and had some fun writing about a panicked astronaut who gets hit by a dust devil to essentially no effect… but then they see a dust storm on the horizon with what appears to be real lightning. While researching this chapter I read a lot about experiments showing that such discharges can occur on Mars, so it’s cool to see my descriptions were accurate!

You can email me at [email protected] (though replies can take a while), and all my social media outlets are gathered together at about.me. Also, if you don’t already, please subscribe to this newsletter! And feel free to tell a friend or nine, too. Thanks!