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  what does LASCO see?
  how does LASCO see the corona?
  blasts from the Sun
  are CMEs dangerous?
  what causes CMEs
  what has LASCO taught us?
  LASCO - the great comet hunter

are CMEs dangerous?

 

All this talk of huge explosions from the Sun sounds frightening. Do any of them ever come in the direction of the Earth? Do any ever hit the Earth?

 

How would we recognise a CME heading for Earth?
Fortunately the answer is fairly simple. If a CME shows up in a LASCO image as a bright ring around the Sun, we can be sure it's not shooting out from the Sun sideways, but is likely to be heading straight for SOHO. Since SOHO is almost directly between the Sun and the Earth, the CME must also be heading straight for us! mouse over arrow This kind of CME is called 'halo CME', because, when it first forms, it looks like halo around the Sun.

 

This mouse over arrow is what happens when a CME hits SOHO.

 

It's not all bad news though. CMEs can produce beautiful effects too, like the aurora or Northern Lights seen in these images. mouse over arrow

 

It’s important that we know when large CMEs are going to hit. LASCO acts as an early warning system.

We can use data from LASCO to make space weather forecasts. This will help operators of satellites. If the space weather forecast is bad, they can prevent damage to their satellites by, for example, shutting them down until the storm has passed.
Find out more about this in the space weather section.

         
You can see more movies in our Gallery   [Movie file 1mb or more - High quality]

Have a look at this movie, which shows a halo CME seen by LASCO. We know it was headed towards SOHO (and the Earth) because a 'snowstorm' was produced in the image when the particles in the CME actually hit the LASCO camera.

 

CMEs travel so quickly through space that it can take only 3 to 4 days for them to reach the Earth.

 
 

 

CMEs can also cause disruption to radio communications and to electrical power networks here on Earth.

   

 

   
 
 

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