Current Solar Wind
Current Solar Wind Readings from DSCOVR via SWPC
Received: Sep 21, 2021 05:42:00 UTC
Bz: 1.63 nT | Bt: 6.39 nT | Density: 9.56 p/cm3 | Speed: 343.10 km/s | Expected Arrival: 73 mins (Sep 21, 2021 06:54:50 UTC)
What's the "secret" to seeing the aurora?
Sky Condition: It should be no surprise that you need good, clear, dark skies in order to see the aurora. Does that mean no clouds at all? Certainly not. High, thin cirrus will provide you with a hazy view of the lights and breaks in low and mid-level clouds can provide a glimpse. However, clear skies are the best for the amazing viewing experience. What about the moon? While you would prefer a moonless night, Lady Aurora does not always wait for the moon to set. The lights may appear fainter with a moonlit sky, but you can still see them if they are active.
Solar Wind Speed: This element of seeing the aurora is a bit trickier. Wind speeds appear to average around 300 kilometers per second (km/s) and the aurora can be visible any time during the night with average wind speeds. The higher the wind speed, the more likely the aurora will drift further south. Why? The wind "blows" the aurora further to the south where more and more people can see it! The two instances we have seen in the Anchorage area lately (January 25 and February 2, 2021) have both had wind speeds in excess of 500 km/s. We had another active aurora on December 23, 2020, but failed to get data from that event to see what it was. It was a bit further north, however, so speeds may have been in the mid-400 to low 500 km/s range. We'll just have to keep track to see!
Solar Wind Density: Like wind speed, density is another tricky factor. From what I have read, our normal density is 3-6 atoms per cubic centimeter (p/cm3). On any given night, you have a chance to see aurora. Thus, further north, I believe the normal density is good. However, more is always better. In the Anchorage area, we have seen good displays when the density is between 8-10 p/cm3.
Bz: The Bz is an oddball, really. Bz is a measure of the orientation of the magnetic fields in the interplanetary magnetic field. Big words, right? A positive number means the fields are oriented to the north and a negative to the south. We want the Bz to be negative. Why? As the solar wind blows, it distorts the magnetic fields and bends them back towards the dark side of the Earth. Eventually, they give way, traverse to the dark side of the Earth, break, and then reconnect. This reconnection of the magnetic fields is what causes the "spark" to begin the auroral displays. And, from what I gather, this can happen multiple times during the night. Lately, with strong solar winds, we have been seeing displays between 7-9pm and then another round beginning around 2-3am; sometimes lasting all night further north. So, Bz is HUGE in allowing us to see very nice auroral displays, regardless of your location.
Patience: I can't say this enough...PATIENCE! You can't go out at 7pm every night and throw in the towel by 9-10pm. On a "normal" night, they begin between 10:30pm and 12:00am in the area, if at all, and then again around 3am. Time it, take a nap, and set yourself up for success. If you are an aurora junkie, you might be running on two hours of sleep at work the next day. Depending on the display, it could be totally worth it!
The below images are forecasts for sky condition and opaqueness of the sky from the National Weather Service's GFS-LAMP product. These are generated by a computer and not based on human interpretation of weather data, so some degree of error does inherently exists. Click on the images for bigger, legible images.