Vivid auroras like those seen in Blakley's images are caused by charged particles from the sun (the solar wind) that interact with the Earth's upper atmosphere (at altitudes above 50 miles, or 80 km), causing a glow.
The particles are drawn to Earth's polar regions by the planet's magnetic field. The auroras over the North Pole are known as the aurora borealis, or northern lights. The lights over the South Pole are known as the aurora australis, or southern lights. When the aurora is most active, it creates a spectacular display of bright colors called the aurora corona.