Let’s take a look at the science behind the Northern and Southern lights, starting with sunspots. Sunspots are black areas that appear on the Sun’s surface. They are darker than other sections of the Sun’s surface because they are cooler spots on the Sun. Sunspots can be seen by projecting an image of the sun on a white surface using a telescope or binoculars. Many sunspots appear on the Sun’s surface during ‘Solar Maximum,’ where flows of magnetic energy rush into and out of the sun. When these become particularly active, they can generate plasma bursts from the Sun in the form of ‘coronal mass ejections,’ which send streams of charged particles rushing towards Earth. These interact with the magnetic field of the planet to produce stunning Aurora shows.
A solar flare is a powerful explosion of light, containing a variety of energy types including radiation, caused by the release of magnetic energy from sunspots. Flares are the most powerful explosive phenomena in our solar system. They appear as glowing spots on the sun and can last anywhere from a few minutes to several hours. The particles released by a solar flare can be seen at nearly every wavelength of the universe. Flares are mostly monitored using x-rays and optical light.
Solar flares are classified according to their brightness, which ranges from 1 to 8 Angstroms. A, B, C, M, and X are types of flares, with A being the smallest and X being the largest. Each category is divided into nine subcategories, such as A1 to A9, B1 to B9, and C1 to C9. This means that a B flare is ten times more powerful than an A flare.
Want to see the current Solar flare index? Click here.
Coronal mass ejections
Strong magnetic fields structure the outer solar atmosphere, known as the corona. The solar atmosphere can unleash burps of gas, known as plasma, and magnetic fields, releasing energy equivalent to 20 million nuclear bombs. These burps are known as coronal mass ejections or CMEs. CMEs are large eruptions that occur near the sun’s surface and are caused by errors in the solar magnetic field. A massive CME can include billions of tonnes of matter. CMEs travel at rates ranging from 250 kilometres per second (km/s) to about 3000 km/s as they leave the Sun. Depending on the eruption’s location, the blast might either avoid Earth or be partially or completely headed towards Earth. When a CME is heading toward Earth, the CME could reach Earth in 15-17 hours or more (depending on speed) and will most likely trigger a geomagnetic storm which causes spectacular auroral phenomena.
Differences Coronal mass ejection and solar flares
There are many different types of eruptions. Solar flares and coronal mass ejections both involve massive energy explosions, however, they’re not the same thing. Both events can occur at the same time – in fact, the most powerful solar flares are almost always associated with coronal mass ejections – but they radiate different things. Solar flares are huge bursts of energy that erupt from the Sun and contain a variety of energy types, including heat, magnetic energy, and ionising radiation. Whereas CMEs are bubbles of superheated gas also known as plasma. Moreover, Solar Flares and CMEs look and travel in different ways, and have different impacts near planets.
Flares can last anywhere from a few minutes to several hours and contain enormous amounts of energy. The light from a solar flare takes eight minutes to reach Earth because it travels at the speed of light. Whereas CMEs take hours before reaching Earth.
Solar telescopes can discern the distinctions between the two types of explosions, with flares appearing as a bright light and CMEs looking like massive fans of gas spreading into space.
What is Kp-index? The Kp-index represents the geomagnetic activity (the disturbance of the earth’s magnetic field) on a scale from 0 to 9, where 0 means low aurora activity and 9 means high aurora activity. A Kp-index of 3 could possibly be seen in Tasmania, whereas a KP-index of 8 could possibly be seen in the South of Queensland. However, geomagnetic activities that reach a Kp-index of 8 are very uncommon. Curious about the current Kp-index? Click here.
There are several magnetometers around the world that non-stop measure geomagnetic activity for a 3-hours period. The magnetometers measure the variance in geomagnetic activities and report the maximum variance of activities to the other magnetometers. The combined data from the magnetometers creates an algorithm which then determines the final Kp-index estimation.
When the Sun releases massive bursts of energy in the form of solar flares and coronal mass ejections, solar storms occur. At a speed of nearly three million miles per hour, these occurrences send a flood of static electricity and magnetic fields toward the Earth. When a solar storm hits the Earth, it frequently causes dazzling auroras that appear in sections of the atmosphere and can be seen near the Arctic Circle (North) and the Antarctic circle (South).
Solar storms are being categorized into 5 different categories, with G1 being the mildest and G5 being the strongest. This scale used for these categories is called the Geomagnetic Storm Scale.
Want to see the current geomagnetic activity? Click here.
Want to learn more? Here are some great websites that could help you out!
- Space Weather Prediction Center
- Space Weather Service
- The Disturbance Storm Time Index