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This figure shows the composition of a large event which was measured by ACE-SWICS on May 3 and compares it to standard solar wind composition (labelled slow solar wind). The Fe and O charge state show that the CME plasma is composed of a very hot (about 2.5-3 million K) and a very cold (less than 0.3 million K) component. Click on image for full size (268K JPEG) Image courtesy of ACE-SWICS

The ACE spacecraft just recorded one of these explosions on May 3, 1998. These CMEs send material flying away from the Sun. Sometimes that material hits the Earth. If the material does hit the Earth, it can cause geomagnetic storms, aurorae or electrical power blackouts.

So we need to know when these CMEs are coming. That is why we have spacecraft like ACE. The ACE satellite is a spaceweather station in orbit. ACE can provide about one-hour advance warning of any major geomagnetic storms.

This figure shows the composition of a large event which was measured by ACE-SWICS on May 3 and compares it to standard solar wind composition (labelled slow solar wind). The Fe and O charge state show that the CME plasma is composed of a very hot (about 2.5-3 million K) and a very cold (less than 0.3 million K) component. Click on image for full size (268K JPEG) Image courtesy of ACE-SWICS

These explosion events were first discovered in the 1970's. Since they were discovered not too long ago, scientists are still finding out about these CMEs. The ACE satellite found that the CME that passed it last month wasn't made up of material that is all the same temperature. Instead, it was found that the CME was made of an extremely hot region, followed by a cooler region and then another hot region of solar material. This discovery could change what scientists know about CMEs and about how CMEs affect the Earth's environment.

CMEs can definitely affect Earth. They can cause strong geomagnetic storms, aurorae or electrical power blackouts. So we need to know when these CMEs are coming. That is why we have spacecraft like ACE. The ACE satellite serves as a spaceweather station while in orbit. ACE can provide about one-hour advance warning of any major geomagnetic storms.

As we near solar maximum, more and more CMEs are likely to occur.

This figure shows the composition of a large event which was measured by ACE-SWICS on May 3 and compares it to standard solar wind composition (labelled slow solar wind). The Fe and O charge state show that the CME plasma is composed of a very hot (about 2.5-3 million K) and a very cold (less than 0.3 million K) component. Click on image for full size (268K JPEG) Image courtesy of ACE-SWICS

These explosion events, first discovered in the 1970's, originate at the Sun's visible surface, the photosphere, and travel upward through its atmosphere, and then into its super-hot corona before speeding out into space, sometimes towards Earth. Before this May 3rd CME hit the Earth, the CME material passed the ACE satellite. On this occasion, the SWICS (Solar Wind Ionic Charge Spectrometer) instrument did not measure one homogeneous mass of material as the CME passed ACE. Instead, it was found that the CME consisted of an extremely hot region, followed by a cooler region and then another hot region of solar material. Further analysis is being done, but this discovery could change what scientists know about CMEs and about how CMEs affect the Earth's environment.

The ACE spacecraft will continue to track the solar wind coming from the Sun while solar activity increases. The ACE satellite serves as a spaceweather station while in orbit. The location of ACE enables it to provide about one-hour advance warning of any major geomagnetic activity that can cause aurorae or power losses here on Earth.

As we near solar maximum, more and more CMEs are likely to occur.