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Aurora Borealis Likely To Be Visible In Southern NY and PA Tonight
New submitter chromaexcursion writes "Several news source are reporting the likelihood of an impressive show of the Aurora Borealis visible as far south as Washington D.C. this evening. Accuweather explains: 'On the Kp index, the flare has been categorized at 6 to 8. This is a scale for measuring the intensity of a a geomagnetic storm. The 6 to 8 rating means that the effects of the radiation will have a greater reach. ... The radiation from such a flare may cause radio wave disturbances to electronics such as cell phones, GPS and radios, causing services to occasionally cut in and out. While traveling slower than was originally anticipated, the flare effects are moving towards Earth at 1000 km per second. ... The lights are currently estimated for 8 p.m. EDT Saturday arrival, with a possible deviation of up to seven hours.' Check the map; if you're in a fair-to-good zone, head out after sunset to see the show."
The first impact of the CME has hit and the boulder Kp is hovering around 3. Watch it here.and here. Here in southern Minnesota, Kp has to hit 6 before we see anything. 5 up on the Canadian border. Good luck spotting those unicorns!
Obi-Wan: "I felt a great disturbance in the Force, as if millions of voices suddenly cried out in terror and were sudden
This doesn't look like a joke, but something does seem off.
On the Kp index, the flare has been categorized at 6 to 8
Flares are not categorized with the Kp index. The Kp index is a scale for rating how large of a geomagnetic storm is going on. it is a non-linear scale of how much the Earth's magnetic field is deviating from typical value, as measured at several locations. Typically to get good auroras further south, you need both a high Kp index, which pushes the parts of the magnetic field lines bringing in solar wind and other stuff further away from the magnetic poles, and a source of particles to actually produce bright aurora. Solar storms do produce both, although there are situations where you can sometimes get one or the other.
Anyway, there several ways flares are rated, but the Kp index is not one of them. But it does factor into what into what to expect as far as aurora at more southernly locations. It is rather difficult to predict accurately from solar activity. The more accurate predictions are on short time scales using satellites in front of the Earth that can measure the solar magnetic field a few hours before variations hit us as carried by the solar wind. You can see the output of a model here, and so far it looks no where near as high as what Accuweather is suggesting. Although that model can be wrong at times, so it could still happen. For predictions and watches based on the space equivalent of weather men, you can find a chart of that here. While two days ago there was a watch made for a G2 level geomagnetic storm, which would be another way of describing a Kp=6 condition, the more recent updates and aurora circle maps show that current conditions are much short of that.