Aurora Stats and Averages

Aurora Stats and Averages

Climatologists study records of Earth's weather to calculate averages and find trends and patterns.I wanted to do the same with space weather to find out how geomagnetic activity varies by year, month, and day. The British Geological Survey (BGS) has been keeping records of geomagnetic activity since 1932. So I imported this 86 years worth of data into a spreadsheet to analyze it, and break it down into graphs and charts. The Royal Observatory of Belgium - SILSO has been recording sunspot numbers for even longer since the 1700's. The effects of the solar cycle become clear in the first 6 graphs below. What is the Solar Cycle? For centuries it has been known that the sun follows a regular pattern of high and low solar activity. This period averages 11 years in length, but can vary from 9 to 13 years long. Solar maximum is defined as the month with the highest sunspot number. Conversely, solar minimum is defined as the month with the lowest...
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KP Index Explained

KP Index Explained

Open full screen map The Kp-index is a scale used to characterize the magnitude of geomagnetic disturbances. A geomagnetic storm starts at Kp5 after which the G-scale is also used. Kp0 = Quiet Kp1 = Quiet Kp2 = Quiet Kp3 = Unsettled Kp4 = Active Kp5 = Minor storm (G1) Kp6 = Moderate storm (G2) Kp7 = Strong storm (G3) Kp8 = Severe storm (G4) Kp9 = Extreme storm (G5) Magnetometers measure the strength of Earth's magnetic field to determine the K-index, which is tied to a specific station. The Kp-index is calculated by combining the data from multiple magnetic observatories around the world to determine the global planetary index.  See the current Kp-index on the Live Data page. The map above shows you what the Kp-index needs to be to see the aurora overhead at a given location. Generally once the Kp-index reaches a certain threshold it will fill the northern half of the sky (in the northern hemisphere) all the way up...
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How to See the Aurora

How to See the Aurora

I recommend reading the What Causes the Aurora post first. Seeing the aurora is simply a matter of being in the right place at the right time. But how do you know where and when to go? What sort of conditions should you be looking for? Live Data The Kp-index is one of the easiest measurements of the aurora to use because it boils all the geomagnetic data down to a simple number from 0-9. On the KP Index Explained page, you can find the minimum Kp number that needs to be reached before you'll see the aurora at a given location. Once you know this number, you can start watching the live data and looking for an increase in geomagnetic activity. At the bottom of that page you can see any watches or warnings that are in effect. The "Text Forecast" tab shows a 3-day and 27-day forecast of geomagnetic activity. You can also sign up for email alerts from NOAA, so you're not caught...
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How to Photograph the Aurora

How to Photograph the Aurora

There are 2 reasons to photograph the aurora. The first is the same reason you'd photograph anything amazing, to preserve the memory and share with others. But the 2nd reason is the northern lights show up much clearer in a picture than they do to the naked eye. This is because a camera can take a long exposure, and the photons from the aurora will accumulate on the sensor, increasing their brightness. The human eye is very limited in what it can see at night. Colors especially are very washed out, but they will show up much better with a long exposure on a camera. Sometimes you may be unable to tell if you are looking at the aurora or something else, but you can use a camera to confirm what you're seeing. So how do you capture the aurora borealis? Keep reading to find out. Required Gear: A camera with manual controls (a DSLR or other large sensor camera is...
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What Causes the Aurora

What Causes the Aurora

Before learning how to see the aurora, first it helps to know where they come from. To understand what causes the aurora first you must know a bit about the sun. The Sun The sun hangs in space 150 million kilometers away from Earth. A ball of hot plasma 1.4 million kilometers wide, it's internal convective currents generate a magnetic field. It rotates on it's axis about once every 27 days. But the equatorial region of the sun rotates faster, while the poles rotate slower. It is this differential rotation that winds up and twists the internal magnetic field into complex loops. These loops emerge above the surface of the sun (the photosphere) as sunspots. Sunspots are easy to observe with either an inexpensive solar filter or by projecting them onto a surface. The outer atmosphere of the sun is known as the corona. It extends millions of kilometers into space. For reasons scientists do not understand, the corona is about 450 times hotter...
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