"Busy old fool, unruly Sun, Why dost thou thus?"
- John Donne (1572-1631) "The Sun Rising"
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Welcome to the CDS website

Launched in 1995, the ESA/NASA Solar and Heliospheric Observatory (SOHO) is the world's largest solar physics space mission and it has revolutionised our understanding of the Sun. The Coronal Diagnostic Spectrometer (CDS) is a unique instrument, designed to detect solar extreme ultraviolet radiation which allows us to probe conditions in the solar corona. The spectra recorded by CDS provide information on temperature, density, elemental composition and flows of very hot plasma trapped in the Sun's magnetic field. The CDS operation is run from RAL, where the requests for observations from a user community of 15 UK institutes and over 60 world-wide groups are coordinated, planned and run.

Latest News: Sun|trek - an educational resource for schools

Sun|Trek image Sun|trek is an exciting new website for school students and teachers about the Sun and its effect on the Earth. Sun|trek has been motivated and inspired by the fantastic images and movies of the Sun taken from space (for example from the SOHO satellite). It is narrated by solar guides (young solar researchers), who not only share the excitement that they feel about working with these solar space projects, but also say a bit about themselves, how they became interested in astronomy and what their other interests are. They are 'role models' who could inspire the younger students.

The detection of magneto-acoustic waves propagating from the chromosphere to the corona using CDS. Left panel: a composite CDS and TRACE multi-wavelength image of an active region. The coincidence of the sunspot umbra, sunspot plume (turquoise), and emerging coronal loop system (blue) is apparent. These are locations where magnetic-acoustic waves have been detected, propagating from the chromosphere to the corona. Right panel: atmospheric structure above a sunspot with increasing temperature, obtained from CDS and other SOHO instruments. More details can be found in Marsh & Walsh (2006).

Selected results and movies from SOHO - courtesy of the SOHO and Instrument teams.

SOHO Spacecraft animation

Our mysterious Sun


The complex & violent solar atmosphere

The quiet and active Sun

Close up on convection cells

Peeling back the solar atmosphere

Temperature mapping the Sun

Solar Tornadoes.

The Vibrating Sun


Coronal Mass Ejection


Driving the Earths Aurora animation

The Comet Neat


Two out of a thousand Comets

The big one


Four Planets & the Plieades

Magnetic Field Structure animation

Surface Magnetic polarities

Problems viewing the movies:
Mozilla,Firefox & Windows Media Player should work fine together
IE & Windows Media Player may have issues:
Either click 'close' on the WMP 'download failed box' then click play on WMP
(Once cached locally the movie should play)
or right click on an image and select 'Save Target as' then save file to disc.
Play the saved file by double clicking on it.
or simply chose the QuickTime option

Some amazing facts about CDS
  • 10,000,000 exposures have been taken
  • 34,000 science studies have been run
  • 240,000 science fits files have been produced
  • 3,500 individual science plans have been made
  • 400,000 command blocks have been sent to CDS by the CDS ground system
  • 400GB of data sent back from CDS
  • 666 reviewed science papers published
    The mechanisms have performed:
  • 24,000,000 mirror steps
  • 7,000,000 slit steps
  • 24,000,000 instrument pointing movements
    and all with just one major service, and that was before launch

A CDS Intrument status page is now online.
The CDS User Guide has been updated with latest GIS information.

We still await the definative orbit information files. Processing of CDS final telemetry continues, though data sets are not being flagged as 'Final' until the orbit files becomes available. View the CD Processing page to see the current processing status