The Sun this past week ending Oct. 21, 2005 has been particularly quiet with just one small sunspot at present, yet there remains activity and motion that we cannot even see. Though it is under the Sun's surface, we can detect it. The Michelson-Doppler Instrument (MDI) on SOHO, using techniques similar to those of seismographs used on Earth to detect earthquakes, can discern wave-like movements inside the Sun. These are called oscillations.

Taking many thousands of data points of these oscillations as his starting point, a solar scientist named Alexander Kosovichev developed a procedure for turning these measurements into sound. He filtered the velocity data at about 3 mHz to select clean sound waves. Then he speeded it up a factor of 42,000 to bring it into the audible human-hearing range (kHz). You can hear it too. Click on the audio file above to hear the throbbing sound of the Sun.

To learn more about this and hear more sound samples, you can go here: http://soi.stanford.edu/results/sounds.html.

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Previous Picks of the Week

SOHO began its Weekly Pick some time after sending a weekly image or video clip to the American Museum of Natural History (Rose Center) in New York City. There, the SOHO Weekly Pick is displayed with some annotations on a large plasma display.

If your institution would also like to receive the same Weekly Pick from us for display (usually in Photoshop or QuickTime format), please send your inquiry to steele.hill@gsfc.nasa.gov.