28 May 2024 - Mission Day: 10406 - DOY: 149

SOHO Sees Right Through the Sun

    Also available: High-resolution TIFF image.
    The upper two images show the magnetic field strength measured with MDI while the active region was facing the Earth - before and after being holographically imaged on the far side, shown in the lower image.
    Movies: MPEG, QuickTime.
    An illustration of how the magnetic fields rotate with the Sun to the far side, where the inset shows the holographic image of the backside.
       Schematic of Helioseismology Technique Movies: MPEG, QuickTime.
    Sound waves from the far side of the Sun are reflected internally once before reaching the front side, where they are observed with MDI.
    Also: High-resolution TIFF image.

Caption: One of the highest hopes for the ESA-NASA SOHO spacecraft is fulfilled with the detection of sunspots on the invisible far side of the Sun. This scientific marvel promises practical benefits. It could give a week's extra warning of possible bad weather in space, to astronauts and to the operators of satellites, power networks and other systems that may be affected by eruptions on the Sun linked to sunspots. The success is announced in the journal Science (10 March) by Charles Lindsey of Tucson, Arizona, and Doug Braun of Boulder, Colorado. They realised that analytical witchcraft called helioseismic holography might open a window right through the Sun. And the technique worked when they used it to decode waves seen on the visible surface by one of SOHO's instruments, the Michelson Doppler Imager or MDI.

"We've known for ten years that in theory we could make the Sun transparent all the way to the far side," said Charles Lindsey. "But we needed observations of exceptional quality. In the end we got them, from MDI on SOHO."

More information is available on these pages:

Instrument:MDI (Michelson Doppler Imager)
Taken: 16 March 1998 - 12 April 1998
Picture credit: SOHO/MDI, ESA, NASA
Images, animations and web page design by Doug Braun, Charlie Lindsey, Mike McClare, Walt Feimer, Steele Hill, Joe Gurman and Stein Haugan


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