More Aurora Science
Space scientists monitor solar activity for many different reasons, and aurora watchers benefit from this information. When a solar event is forecast, odds are that aurora displays will result. For a photographer, it’s helpful to understand the spatial scale of the process. Because charged particles (plasma) travel a lot slower than light, and they can travel from the sun to Earth at different speeds, this delay means satellites can detect these particles and generate forecasts.
The charged particles concentrate in a ring around Earth’s geomagnetic poles, and this oval band constantly expands and contracts. The northern lights appear in regions that are located beneath or near the edge of this oval. A major geomagnetic event – and a resulting expansion of the auroral oval –can give more southerly regions a rare view of the aurora.
The northern lights get all the attention, but a mirror image of the same light show simultaneously appears around the magnetic South Pole. The southern lights, or aurora australis, is the opposite projection that encircles the Earth’s Antarctic regions. Though you’re just as likely to see the southern lights, access will be your challenge. Antarctica is the only land mass under the aurora australis band, though people in New Zealand, Tasmania, Patagonia and even South Africa sometimes get good views of strong aurora. If you’re an aurora fanatic, put the southern lights on your bucket list.
Some aurora terminology:
Solar flare is a bright burst of light and radiation from the sun. This sudden energy release sends clouds of particles into space, often followed by a coronal mass ejection.
Coronal mass ejection or CME is a massive eruption on the sun that also sends solar material into space. CMEs are very large eruptions of the corona, while flares are local events.
Coronal holes are darker, cooler regions on the Sun’s outer atmosphere (the corona) where solar wind can escape at high speeds.
Solar wind is the stream of energized, charged particles released from the sun. This supersonic flow of solar materials made of plasma can cause geomagnetic storms and aurora on Earth.
Plasma is the fourth state of matter. The other three states are solid, liquid and gas. Plasma is most similar to a gas but it behaves differently, such as flowing like a liquid.
Geomagnetic storm is a disturbance to Earth’s magnetic field caused by solar activity. CMEs, flares or coronal holes cause solar wind shock waves that typically strike Earth's magnetosphere 24 to 36 hours later and can have various human impacts.