What does HS stand for?

International contributors from Cuba to Kazakhstan and most parts in between provide essays on topics such as solar filaments and their eruptions, the time-distance helioseismology of sunspots, some peculiarities of research into multi-scale ionospheric irregularities by radio methods, solar type IV bursts at frequencies 10-30 MHZ, and a numerical study of formation and propagation of giant electric jets between a thundercloud and the lower ionosphere.

The study of these and similar waves is called helioseismology.

On board SOHO is the highly sophisticated Michelson Doppler Imager (MDI), an electronic instrument that creates images of the sun's interior by measuring the velocity of sound waves produced by hot, bubbling gases that well up to the surface--a technique called acoustic helioseismology.

Helioseismology -- observations of the way the sun's surface rises and falls in a pattern of oscillations -- provides one of the best checks on these nonstandard models by supplying information about the sun's internal structure, for example, how deep the sun's convective zone goes.

Papers are grouped in sections on instrumentation, convection and sunspots, magnetism of quiet sun and active regions, waves and shocks, chromospheric heating, coronal heating, local helioseismology, emerging flux, reconnection, flares, coronal mass ejections, and solar wind.

The study of the inner sun, known, as helioseismology (SN: 7/2/88, p.

The European Space Agency's Solar and Heliospheric Observatory, scheduled for launch in 1994, will carry three helioseismology instruments (SN: 2/22/86, p.