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Hello, Louise and David here. We are working with colleagues in the UK, USA and Japan on data from a satellite called YOHKOH

David Alexander

YOHKOH was a Japanese satellite designed to analyse X-rays coming from the Sun. It had instruments to take images of the Sun and a spectrometer to provide spectra of the Sun's X-rays. The name 'YOHKOH' is the Japanese for sunbeam and was chosen after a competition run by a Japanese newspaper.

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

Here you can see a movie showing images of the Sun changing from the visible (surface) up to the hot corona, seen by YOHKOH in X-rays.


YOHKOH was launched from southern Japan in August 1991 on a Japanese-built rocket. A picture of the launch is shown above.


Since X-rays in the Sun's corona are emitted by very hot plasma, YOHKOH's images show us where the very hot plasma is and how it moves.

Unfortunately, after over 10 years of operation, control of YOHKOH's pointing was lost and it had to be shut down by the Japanese operators. However, over its lifetime YOHKOH gave scientists much new information about the solar corona and they will be analysing the data for many years to come.



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



If you'd like to know a bit more about what we've learnt from YOHKOH, then have a look at the section on 'Solar Flares' in the 'Hot Solar Atmosphere'.


These are typical YOHKOH pictures of X-rays from the Sun.


Although YOHKOH isn't working anymore, we’re still working with our friends from Japan, the UK and USA on the follow-up mission called Hinode, which was launched in 2006.




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