GONG H-Alpha solar image
radio propagation
Today's Space Weather
Sunday 21 December
last updated 20/2314 UT
Expect moderate to high solar activity. A CME is expected to arrive at Earth today, 21 December. There is a possibility of aurora being observed in southern latitudes such as Tasmania at local night time hours on 21 and 22 December. An X-class flare occurred at 0027UT on 20 December and is expected to have a glancing blow at Earth on 22 December. The solar wind is presently light, but expected to increase to moderate after impact. Short-wave radio fadeouts likely. High-frequency radio communications normal at this time.
What is Space Weather ?

Space weather refers to changes in the space environment, particularly the region between the Earth and Sun. The "solar wind" from the Sun stream past the Earth and is mostly deflected by the Earth's magnetic field, but variations in the solar wind cause changes in the Earth's magnetic field.

solar prominence

Occasionally, a huge release of magnetic energy, called a solar flare, occurs on the Sun. Flares can produce large quantities of x-rays which affect the Earth's atmosphere. They can also accelerate atomic particles (mostly protons) to very high speeds (a substantial fraction of the speed of light!). These high energy particles are dangerous to man and can reach the stratosphere where jetliners fly.

Most aspects of space weather affect us to some extent. The more our society becomes dependent on technology and the more we utilise space, the more we are affected by space weather. Some aspects of space weather are benevolent, and allow activities not otherwise possible such as long range radio communications. Some aspects are benign but fascinating such as the Aurora, and some are malevolent. Like terrestrial weather, it sometimes depends on the situation and the event.

The image below is an artists impression of the solar wind interacting with the Earth's magnetic field.

Solar wind
Combined image of active region 1520 shortly before it unleashed an X-class flare. The image is made up of light in the 171 Angstrom wavelength, and a magnetogram.
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