A Simple guide to Aurora Chasing
A substorm sweeps over South Haven on 10-10-24
I want to start off with some information about the Aurora. The simple answer to what causes Aurora is the sun! The sun has imperfections in its magnetic field which causes sunspots. From those sunspots occasionally eruptions occur called solar flares. Solar flares have several classes. C class, M class, and X class. The large Auroral displays observed this year come from X class flares. There are several phone apps that can alert you of these types of events.
Unfortunately its not as simple as “there is a solar flare, so there will be Aurora!” The factors that must align in order for a solar flare to create aurora include the direction the flare was pointed as well as the presence of a coronal mass ejection with the flare event. This information is all analyzed and summarized by some fine people over at Solar Ham. But in short, the flare must be earth facing, and the coronal mass ejection needs to be a “Full Halo mass ejection” which indicates that it will likely hit Earth.
Once you are nearly certain that the particles are flying in the right direction, you get to wait 48 - 72 hours for those particles to arrive at Earth which may or may not happen. While you are waiting for those charged particles/plasma to show up on Earths Magnetosphere, now its time to check the weather for the next 3 days. There are some weather apps that are better than others. I use an app called “Good to Stargaze” which I pay a subscription for (I think its 27 dollars a year?).
If the conditions look like they will align and you have a chance to get out in the darkness the next obstacle awaits…. THE MOON! At low latitudes its almost not even worth trying unless the moon is less than 3/4 full. So that totally eliminates 25% of all potential time.
So now that we have had a solar flare with an associated coronal mass ejection that was pointed at earth, and our skies are clear and the moon isn’t too bright we move on to our next obstacle which is light pollution. Light pollution will absolutely defeat most in a quest to see the Aurora. Fortunately there is an excellent website that maps light pollution across the world! That website is called Dark Site Finder and is linked. Each city has a “light dome” over it that extends high above the ground. It is best in my experience to try to get north of that dome for Aurora.
Now that you have your dark spot picked out and have scouted it out and ensured that it doesn’t require any trespassing (always scout during the day so you don’t get stuck or lost in the dark). You essentially play a waiting game. Some people have gone to the length to watch satellite data but I just follow the Facebook group “Michigan Aurora Chasers”. The group does live sightings around the state which is really convenient for people like me who don’t want to go spend all night outside unless there is an epic show going to happen. Being in Southwest Michigan, I only go out if all the conditions talked above are aligned and the data starts to look good, and I have seen live sightings on facebook that are close to my location or at least at the same latitude as me. So now that we know we have seen a post with visible aurora at a low latitude….LETS GO CAPTURE IT! I cant believe it took this long to get here.
Capturing a time lapse at an Easement at Cogdal Vineyard during October 2024
Equipment: Sony a7iii, samyang 14mm f2.8 lens
settings: 10 sec Shutter speed, ISO 3200, F2.8
Now that we are out in our spot, its time to capture the Aurora (if it is there). If you are using your phone, ensure your flash is turned off. With most phones these days, if you have a tripod the image will turn out a lot more clear. Here is a sample of an iphone photo handheld with a 3 second shutter speed with no additional editing being done:
A shot of a beautiful pillar of light arching overhead during a substorm on October 10th. This was taken with my cell phone.
The next thing to consider is the Kp index and bZ values. Kp index is a measure of auroral activity and it ranges from 1 to 7. 1 is low and high is 9. I typically do not leave my house unless the kP index is above 5. bZ is a measure of the earths magnetic field. This one must be SOUTH for the aurora to show up.
An example of Kp and Bz measurements found at spaceweatherlive.com
Summary
To summarize everything that I have talked about there is obviously a lot of factors that go into influencing the presence of the aurora
Sunspot activity - must be earth facing, larger solar flares are better (class M or X) with coronal mass ejections - full halo CME has best chance of strong aurora
Moon: less moon is better (50% or less) NASA.gov
Clouds: (50% cloudy or lower needed) Windy.com
Light pollution: Find the darkest spot possible Dark Site Finder
Kp above 5, BC pointing south Space Weather Live
Follow live chasing on “Michigan Aurora Chasers” on Facebook night of
There is an overwhelming amount of data to parse through in most cases, so honestly, if you don’t feel like dealing with all of that, then the easiest thing to do is just follow live chases on “Michigan Aurora Chasers”!
