อภิธานศัพท์ฟิสิกส์ (อวกาศ)

A 3-hourly planetary geomagnetic index of activity generated in Gottingen, Germany, based on the K INDEX from 12 or 13 stations distributed around the world.

In a magnetically bipolar or multipolar SUNSPOT group, the western part precedes and the main spot in that part is called the leader.

Observed in white light, a bright tongue or streaks penetra- ting or crossing SUNSPOT UMBRAe. The appearance of a light bridge is frequently a sign of impending region division or dissolution.

The edge of the solar DISK.

A solar FLARE seen at the edge (LIMB) of the sun.

A system of loop prominences associated with major FLARES.

That portion of the radio frequency spectrum from 30 to 300 kHz.

The optimum HIGH FREQUENCY radio wave with a 3000 km range, which reflects only once from the IONOSPHERE (single hop transmission).

A geomagnetic and/or cosmic storm has been associated with this flare.

A relatively smooth excursion of the H (horizontal) component (see GEOMAGNETIC ELEMENTS) of the geomagnetic field away from and returning to quiet levels.

Solar magnetograms are a graphic representation of solar mag- netic field strengths and polarity.

The boundary layer between the SOLAR WIND and the MAGNETO- SPHERE.

The magnetic cavity surrounding the earth, carved out of the passing SOLAR WIND by virtue of the GEOMAGNETIC FIELD, which pre- vents, or at least impedes, the direct entry of the SOLAR WIND PLASMA into the cavity.

This flare is the basis for the forecast of geomagstorm, cosmic storm and/or protons in the earth's vicinity.

That portion of the radio frequency spectrum from 0.3 to 3 MHz.