Space Weather
A vulcanic eruption on the Sun
posted: June 09, 2011 - updated: June 10, 2011
On June 07, 2011, there was a spectacular plasma eruption on the Sun. The shock ahead of the plasma cloud skimmed Earth on June 09, 20:00UT. We give a chronological order of how the Space Weather Forecast Centre of Belgium handled the event.

June 07, 08:00UT - 10:00BLT

A radio astronomer of the Solar-Terrestrial Centre of Excellence detected a burst of radiation in the solar measurements made in Humain, Belgium. He alarmed the space weather forecaster on duty.
The space weather forecaster checked satellite data. There was a flash of light, a flare of the level that is not exceptional. But the high speed protons did arrive at Earth almost immediately after the peak of the flare. With help of telescopes monitoring the space around the Sun, the forecaster could identify a plasma cloud. The movie of the solar surface at the moment of the outburst of material was spectacular: blobs of plasma were ejected, a part of it fel fountain wise back on the solar surface. Our instrument SWAP that flies on the satellite PROBA2 filmed the eruption in the UV. But, a large part of the plasma was ejected into the wide space and had an estimated speed of 1000 km/s. Because the plasma cloud is relatively wide, it might hit the Earth with a glancing blow. It is almost impossible to predict the strength of the magnetic disturbances on Earth.
June 07, 08:46UT - 10:46BLT

The forecaster sent an alarm that was distributed to registered users by email and posted on the website.
June 07, 16:01UT - 18:01BLT

The software CACTus confirmed the presence and the speed of the plasma cloud. An automated email alert was sent to registered users.
June 08, 06:46UT - 08:46BLT

The forecaster noted a magnetic structure bumping on the magnetic shield of the Earth. This magnetic structure was not linked with the plasma cloud that left the Sun on June 07.
June 09, 20:00UT - 22:00 BLT

The ACE satellite in front of Earth felt the glancing blow of the plasma cloud. ACE flies in the L1 point, in front of the magnetosphere and the Earth. It takes solar plasma travelling with a speed of 400 km/s about 1 hour to bridge the distance between L1 and the Earth. The shock and the cloud that left the Sun on June 07 skimmed along the Earth's magnetosphere. The response of the global magnetic field of the Earth to this disturbance is limited.
Two very nice movies made by the SWAP telescope onboard of PROBA2. You see a 'stretched' Sun. The eruption ressembles to a magma outburst of a vulcano: it is mass that is ejected. Most of the mass is carried on top of the solar wind towards Earth. Part of it falls back into the corona: you see it as a black rain. The black/colder plasma plonges back and creates a wavy like feature.
More information on the PROBA2 website