top menu
bottom menu

SOHO / SWAN

SOHO/SWAN Map with Comet Hyakutake
SWAN Full-Sky-Map with Comet Hyakutake 1996-03-28

Since 1989 the Solar Heliospheric Observatory SOHO was designed and realized in cooperation between ESA, NASA and research institutes of many countries.

In cooperation between the French Service d'Aeronomie in Paris (SA) and the Finnish Meteorological Institute in Helsinki the Solar Wind ANisotropy monitor was designed and built. Principle Investigator was Jean-Loup Bertaux, SA.. The French team was responsible for the detectors, integration and testing of the instrument, the Finnish side as cooperation between VTT Espoo, VTT Oulu, FMI Helsinki and several Finish companies designed and built the electronics, the flight software and the ground segment.

After the launch on December 2, 1995, SOHO and SWAN were continuously operational, generating a completely new understanding of the Sun. Some selected images can be found on this FMI-server.

ESA / SOHO / Solar Wind Anisotropy instrument (SWAN)

The space weather predictions can be made from the images accessible through the first column "TWO SIDES IMAGES". As the Sun rotates in both half-images from the left to the right, active sunspots indicated by intensive UV in the far side image and moving towards the right edge will become visible from Earth when they move off the screen and appear in the near-side image at the left edge. The active area on the Sun is directly centered on the disk as seen from Earth when the intensity maximum in the near-side image is in its center. Depending on the solar wind speed the particle-caused effects can be felt on Earth 1.5 to 2 days later. A sustained active area seen in the center of the far side image will effect the Earth about 15 days later, assuming a fast solar wind of about 900km/s associated with the active area.For examples and interpretation details please see the dedicated sub-page for SOHO/SWAN Space Weather Predictions.

Near real-time data for comet observation and solar wind distribution maps can be accessed via the French instrument web site.

UV fluxes in the direction of the planets in the solar system, scaled to 1 AU distance from the Sun, can be found as list for each day and a graph covering the six years.

Current and archived observations of the other SOHO instruments can be found via the SOHO home page.


From January 2013 until March SWAN was observing comets PanSTARRS and LEMMON as they crossed the sky in Earth's southern hemisphere. An animation is available here.