<h3>Never drive a car which is larger than a football field during a solar storm</h3>
<p>Otherwise, don't worry about it.</p>
<p>The answer to <a href="https://earthscience.stackexchange.com/q/19303/6031">Does a geomagnetic storm visibly deflect a compass?</a></p>
<p>shows the plot below which was a very large event.</p>
<p>It looks like the fastest change was about 200 nT per minute or about 3 x 10<sup>-9</sup> Tesla/second. For a 6 square meter car that's an electric field around the car's perimeter of about 20 nanovolts all the way around, inducing a minuscule current, probably below that due to galvanic effects (dissimilar metals, rain, salt, rust, dirt).</p>
<p>You need a big antenna to pick it up. Since the area increases faster than the perimeter, if your car were 2,000 km by 3,000 km that would be about  20,000 volts! Of course a real circuit (a continental-sized power grid) presents substantial conductivity, so you wouldn't necessarily see 20 kV lightning, but you will see blown transformers and switching stations because of the induced current overloading.</p>
<p><a href="https://i.sstatic.net/XIWAM.png" rel="nofollow noreferrer"><img src="https://i.sstatic.net/XIWAM.png" alt="enter image description here" /></a></p>
<p><a href="https://www.intermagnet.org/data-donnee/dataplot-1-eng.php?year=2003&amp;month=10&amp;day=29&amp;start_hour=0&amp;end_hour=24&amp;filter_region%5B%5D=America&amp;filter_region%5B%5D=Asia&amp;filter_region%5B%5D=Europe&amp;filter_region%5B%5D=Pacific&amp;filter_region%5B%5D=Africa&amp;filter_lat%5B%5D=NH&amp;filter_lat%5B%5D=NM&amp;filter_lat%5B%5D=E&amp;filter_lat%5B%5D=SM&amp;filter_lat%5B%5D=SH&amp;sort=iaga&amp;iaga_code=LER&amp;type=dif&amp;fixed_scale=0&amp;format=png" rel="nofollow noreferrer">Source</a></p>
<p>Of course, if your car has a magnetic compass stuck to the windshield (my grandfather's car did) it might show several degrees of deflection, but that's probably buried in the errors caused by the <a href="https://www.sbg-systems.com/support/technology/handle-magnetic-disturbances/" rel="nofollow noreferrer">soft-iron effects</a> of the car's magnetic frame itself.</p>
<ul>
<li><a href="https://electronics.stackexchange.com/q/38316">Would a digital compass work reliably when installed in a car?</a></li>
</ul>
<p><a href="https://i.sstatic.net/Gh0kx.jpg" rel="nofollow noreferrer"><img src="https://i.sstatic.net/Gh0kx.jpg" alt="enter image description here" /></a></p>

CC BY-SA 4.0
2021-08-30T08:03:47.733Z
2021-08-30T08:12:22.863Z
2021-08-30T08:12:22.863Z
uhoh
<p>With the solar cycle now leading to an increase in flare activity, one naturally starts to think the effects of a large solar flare heading this way.</p>
<p>While major flares like the Carrington Event are well described, along with the impact in NE Canada in 1989, what I have had some trouble finding is the effect of a large solar flare on modern motor vehicles. Would a large solar flare cause the batteries in a Tesla to explode? Would it destroy the electronic ignition in a Honda Accord? Would we even be able to turn on and drive a modern car (use a 2015 Honda Accord as a reference)?</p>
<p>I looked through some recent posts - <a href="https://astronomy.stackexchange.com/questions/14935/how-bad-could-we-reasonably-expect-a-solar-flare-to-impact-earth-and-what-can-b">here</a> and <a href="https://astronomy.stackexchange.com/questions/12118/can-a-solar-flare-destroy-every-electronic-item-on-earth">here</a>, but didn't find a good answer.</p>

CC BY-SA 4.0
2021-08-29T19:19:32.933Z
Here is a source, but I'm not sure how authoritative it is https://integratedskillsgroup.com/2021/06/mythbusting-the-carrington-event-and-solar-cycle-doom/
James K
CC BY-SA 4.0
2021-08-29T19:36:35.440Z
That's a pretty good article. My follow up question is then, why not? Why wouldn't cars be affected? What sort of solar flare would be needed for cars to have problems?
FontFamily
CC BY-SA 4.0
2021-08-29T19:36:49.090Z
Also, please list your answer below so that I can mark it as correct.
FontFamily
CC BY-SA 4.0
2021-08-29T19:39:12.777Z
I don't have an answer.  That source says that even in much more extreme emp attacks most cars just needed to be restarted.  But the research wasn't done on a 2015 Accord, So in truth I don't know the answer.
James K
<the-sun><solar-flare><flare>
What would be the effect of a large solar flare on motor vehicles?
FontFamily
# What would be the effect of a large solar flare on motor vehicles?

(Asked by: username_0 on 2021-08-29)

With the solar cycle now leading to an increase in flare activity, one naturally starts to think the effects of a large solar flare heading this way.

While major flares like the Carrington Event are well described, along with the impact in NE Canada in 1989, what I have had some trouble finding is the effect of a large solar flare on modern motor vehicles. Would a large solar flare cause the batteries in a Tesla to explode? Would it destroy the electronic ignition in a Honda Accord? Would we even be able to turn on and drive a modern car (use a 2015 Honda Accord as a reference)?

I looked through some recent posts - [here](https://astronomy.stackexchange.com/questions/14935/how-bad-could-we-reasonably-expect-a-solar-flare-to-impact-earth-and-what-can-b) and [here](https://astronomy.stackexchange.com/questions/12118/can-a-solar-flare-destroy-every-electronic-item-on-earth), but didn't find a good answer.

**Tags:** the-sun, solar-flare, flare
> **Comments:**
> **username_1**: Here is a source, but I'm not sure how authoritative it is https://integratedskillsgroup.com/2021/06/mythbusting-the-carrington-event-and-solar-cycle-doom/  
> **username_0**: That's a pretty good article. My follow up question is then, why not? Why wouldn't cars be affected? What sort of solar flare would be needed for cars to have problems?  
> **username_0**: Also, please list your answer below so that I can mark it as correct.  
> **username_1**: I don't have an answer.  That source says that even in much more extreme emp attacks most cars just needed to be restarted.  But the research wasn't done on a 2015 Accord, So in truth I don't know the answer.  

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## 1 answers

### Answer by username_2 on 2021-08-30. Score: 4 | Accepted answer

### Never drive a car which is larger than a football field during a solar storm

Otherwise, don't worry about it.

The answer to [Does a geomagnetic storm visibly deflect a compass?](https://earthscience.stackexchange.com/q/19303/6031)

shows the plot below which was a very large event.

It looks like the fastest change was about 200 nT per minute or about 3 x 10-9 Tesla/second. For a 6 square meter car that's an electric field around the car's perimeter of about 20 nanovolts all the way around, inducing a minuscule current, probably below that due to galvanic effects (dissimilar metals, rain, salt, rust, dirt).

You need a big antenna to pick it up. Since the area increases faster than the perimeter, if your car were 2,000 km by 3,000 km that would be about 20,000 volts! Of course a real circuit (a continental-sized power grid) presents substantial conductivity, so you wouldn't necessarily see 20 kV lightning, but you will see blown transformers and switching stations because of the induced current overloading.

[![enter image description here](https://i.sstatic.net/XIWAM.png)](https://i.sstatic.net/XIWAM.png)

[Source](https://www.intermagnet.org/data-donnee/dataplot-1-eng.php?year=2003&month=10&day=29&start_hour=0&end_hour=24&filter_region%5B%5D=America&filter_region%5B%5D=Asia&filter_region%5B%5D=Europe&filter_region%5B%5D=Pacific&filter_region%5B%5D=Africa&filter_lat%5B%5D=NH&filter_lat%5B%5D=NM&filter_lat%5B%5D=E&filter_lat%5B%5D=SM&filter_lat%5B%5D=SH&sort=iaga&iaga_code=LER&type=dif&fixed_scale=0&format=png)

Of course, if your car has a magnetic compass stuck to the windshield (my grandfather's car did) it might show several degrees of deflection, but that's probably buried in the errors caused by the [soft-iron effects](https://www.sbg-systems.com/support/technology/handle-magnetic-disturbances/) of the car's magnetic frame itself.

* [Would a digital compass work reliably when installed in a car?](https://electronics.stackexchange.com/q/38316)

[![enter image description here](https://i.sstatic.net/Gh0kx.jpg)](https://i.sstatic.net/Gh0kx.jpg)


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