what has LASCO taught us?

If we want to learn what effect CMEs could have on the Sun and the Earth we need to know how often they happen. LASCO saw about one CME every day during the quiet part of the solar cycle (1996). At the maximum of solar activity (2001) it saw many CMEs every day.

By studying images like this, we have learned that a lot of CMEs accelerate as they move away from the Sun. They usually end up travelling at about 450 km/s.

This movie is made up from images taken by LASCO. The time (hour:mins) is given on each image. See how fast the CME is moving. Try the classroom project to measure the speed of a CME.

We can see more CMEs with LASCO than with earlier instruments because it's much more sensitive. We can watch CMEs as they move far into space and, because LASCO watches the Sun nearly all the time, it can give us warnings of all solar storms which are likely to hit the Earth.

One day we hope to be able to predict accurately when CMEs are likely to erupt and travel towards Earth. This is important since the charged particles in CMEs can cause a lot of disruption to modern communications and power lines. Hundreds of CMEs have so far been seen by LASCO giving us a new and spectacular view of the Sun's behaviour.