Home » Glossary



Corona – The Sun’s corona is the outermost part of the Sun’s atmosphere. It is usually hidden by the bright light of the Sun’s surface.

Coronal Mass Ejections (CME) – A coronal mass ejection (CME) is a significant release of plasma and accompanying magnetic field from the Sun’s corona into the solar wind.


Geomagnetic storm – A geomagnetic storm, is a temporary disturbance of the Earth’s magnetosphere caused by a solar storm, which can affect radio communication, power grids, create auroras and much more.


Ionosphere – The ionosphere is a higher region in the Earth’s atmosphere (50 – 1000km) and is the region where aurora form. It is ionised by solar radiation, and has practical importance because it helps propagate radio waves.


Magnetosphere – A magnetosphere is the area of space, around a planet, that is controlled by the planet’s magnetic field. The shape of the Earth’s magnetosphere is a distorted sphere as a result of being blasted by solar wind.


Photosphere – The photosphere is the lowest layer of the Sun’s atmosphere — the innermost layer we can observe directly. The term photosphere means “sphere of light” and is the layer where most of the sun’s energy is emitted. It takes about eight minutes for sunlight from the photosphere to reach Earth.


Satellite drag Drag is a force on an object moving through a fluid (air). It acts opposite to the direction the object is travelling and slows the object, in this case a satellite.

Solar cycle – The solar cycle is an approximately 11-year cycle experienced by the Sun. During the cycle, the Sun’s stormy behaviour builds to a maximum, and the Sun’s magnetic field flips, the Sun then settles back down to a minimum before another cycle begins.

Solar flare – A solar flare is an intense eruption of electromagnetic radiation in the Sun’s atmosphere. Flares occur in active area and are often, but not always, accompanied by coronal mass ejections and other solar phenomena. The occurrence of solar flares varies with the solar cycle.

Solar maximumSolar maximum is the regular period of greatest solar activity during the Sun’s 11-year solar cycle, during which a large numbers of sunspots appear.

Solar minimum Solar minimum is the regular period of least solar activity during the Sun’s 11-year solar cycle, during which sunspot and solar flare activity diminishes, and often flares do not occur for days at a time.

Solar wind – The solar wind is a constant stream of charged particles released from the corona, the upper atmosphere of the Sun. This plasma mostly consists of electrons, protons and alpha particles.

Sunspot Sunspots are phenomena on the Sun’s photosphere that appear as temporary spots that are darker than the surrounding areas. They are areas of reduced surface temperature caused by concentrations of magnetic flux that stop the movement of heat.