Northern Lights Now – Late 2019 and early 2020 mark the depths of the solar minimum and the transition from solar cycle 24 (SC24) to solar cycle 25 (SC25). During the transition, solar scientists watch active regions and identify them as part of the new cycle or the old cycle. Aurora hunters and space weather enthusiasts can follow along and track the progression of the solar cycle as there are more and more new cycle active regions.
Is this active region part of the new solar cycle?
Active regions that are part of the new solar cycle appear closer to the Solar North or South Poles – at higher latitudes – and they have reversed magnetic orientation from the ARs in the previous solar cycle.
Over the course of the cycle active regions appear progressively closer to the equator. At the turn of the solar cycle, new cycle ARs start appearing far from the equator. This can be seen in the Solar Cycle Butterfly Diagram from NASA below. Note the solar cycles are numbered on the lower graph, while the upper graph shows the latitude of the Sunspots at that time.
At the solar maximum of each solar cycle, the Sun’s polarity flips. At solar minimum, the orientation of active regions also reverses. For ARs, the flip means that the western most (leading) part of a active region in the new cycle will have the opposite polarity of the leading edge of ARs from the old cycle. That sounds complicated, so here is an example (click to zoom):
The example above shows two recent ARs from the current transition period. On the left is an HMI magnetogram image of AR 12723 from SC24 on Oct 30, 2018. On the right is an example from SC25, AR 12753 from around Christmas 2019. Notice that on the left image, blue and green indicating positive polarity are on to the West (right, leading) of the region while negative polarity represented as Red and Yellow are to the East. In the right image, Active Region 12753 from Christmas 2019 is from SC25. The polarity is reversed with yellow and red leading the way on the western flank of the active region. Also note that AR12753 is at a high latitude centered around 34 degrees south, while AR12723 is close to the solar equator.
In summary, Active regions can be identified as part of the new cycle if they meet these two criteria:
The AR should appear at a high latitude (closer to the pole), generally around 30 degrees.
It should have the reverse polarity from the previous solar cycle.
Northern Lights Now – It has been such a treat attending the Space Weather Workshop in Boulder Colorado. It is exciting to watch the ideas and collaboration arise as this wonderful community of academic, government, commercial, and enthusiast space weather stakeholders collaborate.
As I’ve been talking with people and explaining NLN, I’ve realized that I need to have a simple central place to access some of the more scicom-ready data visualizations, stories, videos, and just plain cool examples as a jumping off point. This blog entry is that.
Your best bet for determining if there is currently aurora activity is to take a peak at the current KP value. The chart on that page shows the current KP and the expected KP over the next 30-75 minutes. KP is a global scale that ranges from 0 to 9, the higher the value, the more active the aurora is and the closer to the equator it may be visible.
Once you know the current KP, you will want to know if it is possible to see aurora where you are at that KP. This map helps with that:
Find your location on this map, If you are in the Northern Hemisphere the KP level you need is the line to the south of your location. Likewise, if you are in the southern hemisphere the value you need is on the line to the north of your location.
Finally, check your weather. Aurora displays are high in the atmosphere. If it is cloudy, the aurora will be above the clouds and you will not be able to see them.