UPDATE, August 4: Auroral displays have been seen overnight across Europe and the northern USA as predicted. Watch out for more!

A blast of violent space weather could hit the Earth tomorrow following two massive explosions on the Sun. NASA astronomers witnessed a huge flare above a giant sunspot the size of our planet and linked to an even larger eruption across the surface of Sun.

The Sun viewed on August 1 from SoHo (ESA/NASA)

By chance, the explosions were aligned towards Earth, sending a solar tsunami racing millions of miles across space.

Experts estimate a wave of supercharged gas called plasma will reach us this Tuesday when it will buffet the natural magnetic shield protecting Earth. It could trigger spectacular displays of the aurora or northern and southern lights.

The solar outbursts on Sunday August 1 were recorded by several satellites including NASA’s new Solar Dynamics Observatory which watched its shockwave rippling outwards. The flare over the sunspot was swiftly followed by an eruption 250,000 miles (400,000 km) away in a feature called a filament

UK solar expert Dr Lucie Green, of the Mullard Space Science Laboratory, in Surrey, followed the flare-ups using Japan’s orbiting Hinode telescope.

She said last night: “What wonderful fireworks the Sun has been producing! This was a very rare event – not one, but two almost simultaneous eruptions from different locations on the sun were launched toward the Earth.

“These eruptions occur when immense magnetic structures in the solar atmosphere lose their stability and can no longer be held down by the sun’s huge gravitational pull. Just like a coiled spring suddenly being released, they erupt into space.

“It looks like the first eruption was so large that it changed the magnetic fields throughout half the Sun’s visible atmosphere and provided the right conditions for the second eruption. Both eruptions could be Earth-directed but may be travelling at different speeds. This means we have a very good chance of seeing major and prolonged effects, such as the northern lights at low latitudes.” (Update, August 4: Dr Green’s subsequent analysis of satellite data reveals that there were four eruptions!)

Dr Green pointed out that if the eruptions do collide with the Earth’s magnetic field the conditions need to be right for there to be an effect like the northern lights. Specifically, the magnetic field at the front of the eruption needs to be pointing north. For latest news on the eruptions, check out Spaceweather.com.

Scientists have warned that a really big solar eruption, like the Carrington Event witnessed from Surrey in 1859, could destroy satellites and wreck power and communications grids around the globe if it happened today.

Such an event would be the biggest disaster ever to hit mankind, preventing the production of essential supplies including food, water and medicines. Other eruptions have been observed directed towards us but thankfully less severe.

• Discover space for yourself and do fun science with a telescope. Here is Skymania’s advice on how to choose a telescope. We also have a guide to the different types of telescope available. Check out our monthly sky guide too!