What are Solar Waves?
(by Amara Graps)
There are so many different kinds of "solar waves," so one you would need to be specific on the sort of wave that one is looking for. Our Solar Oscillations Group have some technical Web pages that I will list here, but I will also try to give the general idea of those pages so you can browse the links at your leisure.
HelioseismologyThe following URL gives an overview of helioseismology with links to more explanations.
Helioseismology is the science of oscillations or vibrations in the Sun, and those oscillations are caused by waves in the Sun (solar waves). We study waves in the Sun with similar techniques as those used by geologists who study waves in the Earth (earthquakes).
"Internal Ray Paths" (of Solar Waves)The waves described at the following Web page are the main type of waves of which heliosmologists are interested (although helioseismologists are interested in many other types of waves in the Sun, as well.).
On the above Web page we describe the following waves.
"Acoustic waves" are the sort of waves that humans' ears are sensitive to, and of which enable us to hear sounds. The Sun's acoustic waves, though, are at too low a frequency for us humans to be able to hear, so we have to "speed up the waves" in order for us to hear solar waves. These acoustic waves generate standing wave patterns called "p-mode" oscillation patterns, of which we can detect with our MDI instrument on the SOHO spacecraft.
Would you like to hear some of the Sun's waves?
"Gravity waves" are the sort of waves in which gravity is the restoring force. There are actually two sorts of gravity waves.
The first type of gravity wave is the sort of wave that are like those waves on the surface of a lake: surface gravity waves. These "surface gravity waves" are detectable with our MDI instrument on the SOHO spacecraft (you can see the SOI page again.).
There are also deep Sun-penetrating gravity waves (with gravity as the restoring mechanism) that generate oscillation standing patterns called "g-modes" that have not been detected with confidence yet (they are hypothetical at this point, but we are looking hard for them).
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Special Thanks to A. Graps