Instruments

LASCO

Instruments

LASCO

Report on the ‘Halloween Event’

On October 28^th, 2003, an enormous Coronal Mass Ejection erupted from the surface of the sun. It took three days to arrive at the earth, and when it did so, there were great disturbances in the earth’s magnetosphere.

The first instrument to detect these phenomena was NASA’s/ESA’s solar observatory, SOHO. The images to the side represent three instruments (C2, C3, EIT and MDI). These images show that around 11:12 on the 28^th October 2003, there was an enormous Coronal Mass Ejection erupting off the surface of the sun.

It is well known that, on average, there is at least one Coronal Mass Ejection per day, so various instruments were needed to determine whether or not this ‘halo’ CME (which are rarer than a solo CME) was in the direction if the earth.

The second instrument to detect this halo event was the spacecraft ACE (see below). It can be concluded that the CME is passing the ACE craft because the magnetic field reading shows a surge (the near straight line going straight up) and then this increased level sustains. This happened because as the CME passed the spacecraft (at speeds of approximately 7.5 million km an hour) the magnetic field that surrounds the debris increases the levels of the magnetic field in the area. The final indication of this ejection would have been at the Wind spacecraft. Unfortunately, because of the high amount of particles in the oncoming CME bombarded this spacecraft, so the sensors onboard could not operate correctly. When this anomaly did reach the earths magnetosphere, it caused great disturbances.

Figure 1 shows this Coronal Mass Ejection thought the ‘eyes’ of the C2 Coronagraph, which is a part on LASCO instrument on SOHO. The ‘snow’ effect on the fourth image appears due to the fact that the SOHO spacecraft was bombarded with particles from the approaching CME.

Figure 2 shows the CME in progressive stages. The 1^st image (MDI) shows that there is a large sunspot being formed, the second image (EIT) shows the sunspot progressing even further, hence the great brightness, and the following to images (C2, C3 respectively) show the CME leaving the surface of the sun.

Figure 3 shows data from the ACE spacecraft. It can be analysed that there are two shocks (where the two arrows are), which would suggest that there were two CME’s approaching the earth. We know they are shocks in the magnetic field because the line goes straight up, and then sustains, which suggests an increase in magnetic activity.

When this magnetic storm did finally hit the earth’s magnetosphere, great damage and disturbances were caused. When the CME’s magnetic field collided with the earths, an enormous magnetic storm took place. This caused a Mars-bound spacecraft to temporarily shut down, and it may have caused two Japanese satellites to gain permanent damage.

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