Auroras possible

Powerful solar storm hits Earth this weekend

NASA's SDA spacecraft captured this powerful solar flare - the bright flash in the image on the right - on Thursday.

(Bild: NASA/SDA/AIA)

Six striking solar flares will cause what is believed to be the strongest solar storm since 2005 at the weekend. This increases the chances that auroras may even be visible in the Alpine region and thus also in Austria.

Our central star is currently particularly active. Several (currently six, but there could be more) notable eruptions (technically known as CMEs, note) have been observed on the surface of the sun - just in the region facing the Earth.

On Thursday, NASA's Solar Dynamics Observatory (SDO) probe recorded images of a category X1.1 solar flare - the strongest eruption category - and transmitted them to Earth. According to the Space Weather Prediction Center (SWPC) of the National Oceanic and Atmospheric Administration (NOAA), energy eruptions of this magnitude can cause, among other things, brief radio blackouts on parts of the Earth.

Sun is currently quite active
Such explosions are perfectly normal, but have been occurring more frequently recently because the sun is reaching the maximum of its eleven-year cycle during these months. The particles that were thrown into space with the explosions are now on their way to Earth and are expected from Friday evening, according to forecasts (the animation above only looks at three of the six CMEs currently observed, note).

When the solar storm reaches Earth, the particles will cause several effects such as communication disruptions. Through interactions with the Earth's magnetic field, they also cause a significant increase in auroral activity, for example. These may also be visible in the Alpine region.

Northern lights, recorded over Austria

(Bild: panomax.com)

Minor outages of shortwave radio possible
According to Spaceweather.com, the solar storm may also lead to an outage of shortwave radio transmissions in the two polar regions of the earth. The reason: the Earth's magnetic field directs many of the incoming protons to the poles, where they then cancel out radio signals below 30 megahertz (MHz).

Solar activity - and therefore the probability of solar storms - is linked to the frequency of sunspots. According to data from the US National Oceanic and Atmospheric Administration (NOAA), the number of sunspots is currently higher than it has been for more than 20 years. The more sunspots there are, the more likely solar flares are.

What is a solar storm?

A CME (coronal mass ejection) is a large-scale solar flare in which plasma, consisting mainly of electrons and protons, is ejected. CMEs move through space at speeds of up to 2000 kilometers per second. The emission sources are usually so-called sunspots, whose eruptions are also known as flares.

Particles traveling at up to 120,000 km/h
High-energy particles with a mass of several tens of billions of tons can be hurled into space. They can - at a speed of up to 2000 km/s (120,000 km/h) - reach the Earth, some 150 million kilometers away, within hours to days.