The Sun makes itself known throughout much of the Solar System by the influence the solar wind of high-speed charged particles constantly blowing off the Sun. The solar wind may be viewed as an extension of the outer atmosphere of the Sun (the corona) into interplanetary space.
Magnetic field lines
in the solar corona
The adjacent image shows an enhanced image of the solar corona. In this image
the magnetic field lines of the corona correspond approximately to the boundaries
between regions of different color
(more info). Notice that in the equatorial regions the field
lines traced by these color boundaries tend to form closed loops, indicating the
trapping of coronal gas.
The adjacent animations simulate the variation by month of the ionosphere for two different years:
1. The year 1990 (upper image), which was
a period of high solar activity with many (150) sunspots.
The plots show electron density contours, which are an indication of the amount of ionization in the atmosphere. Yellows and reds indicate larger ionization and blues and greens indicate smaller ionization. Notice the substantial differences in these two animations, with much stronger atmospheric ionization in the upper image (the active Sun of 1990) than the lower image (the quiet Sun of 1996).
The level of solar activity has similar effects on related phenomena such as Earth's auroras.
Space Weather Outlook
SOLAR ACTIVITY IS EXPECTED TO REMAIN
LOW. REGIONS 8142 AND 8143 COULD PRODUCE ISOLATED C-CLASS FLARES.
THERE IS ALSO A SLIGHT CHANCE FOR AN M-CLASS FLARE FROM EITHER
THE GEOMAGNETIC FIELD IS
EXPECTED TO BE MOSTLY QUIET THROUGH 28 JANUARY. A DISTURBANCE IS
EXPECTED DURING 29 - 30 JANUARY IN RESPONSE TO THE PARTIAL-HALO CME
THAT OCCURRED ON 25 JANUARY. UNSETTLED TO MINOR STORM LEVELS ARE
EXPECTED DURING THE DISTURBANCE.
THE GEOMAGNETIC FIELD IS EXPECTED TO BE MOSTLY QUIET THROUGH 28 JANUARY. A DISTURBANCE IS EXPECTED DURING 29 - 30 JANUARY IN RESPONSE TO THE PARTIAL-HALO CME THAT OCCURRED ON 25 JANUARY. UNSETTLED TO MINOR STORM LEVELS ARE EXPECTED DURING THE DISTURBANCE.
In this report, the region numbers refer to active areas on the Sun, C and M are classifications of solar flares, and CME stands for a coronal mass ejection. As noted above in conjuction with the ill-fated Telstar 401 satellite, "space weather" may have non-trivial practical consequences.