Satgen 533  Our Variable Star  by GM4IHJ  (BID SGEN533)  1999-06-12

Sent out to Jupiter to use the big planets gravity to shove its orbit
out of the ecliptic plane. The European Space Agencys Ulysees Solar
Polar satellite then returned sunwards in an orbit which has had it
travelling over the Solar Polar regions . Regions which cannot be
directly observed from the Earth.

The mission has had an unexpected byproduct, in that as Ulysees
travelled from pole to pole, it covered all solar latitudes. Revealing
that the radial component of the solar magnetic field was relatively
constant irrespective of latitude. From which it follows that readings
of the strength of this field as it reaches the Earth, can be taken as
a useful record of solar magnetism whatever the Sun Earth orientation.
So it now becomes possible to extend recent space measurements
backwards through terrestrial measurements taken at near antipodeal
locations in England and Australia since 1868.  These measurements
show that the strength of this general solar magnetic field has
doubled in the last 100 years. This solar field is stretched out by
the expanding solar corona and the solar wind , and its subsequent
impact with the Earths magnetic field is important in respect of the
geomagnetic activity which ensues.

Coupled with this doubling of the solar magnetic field strength, the
number of sunspots being recorded has doubled over this same 100 year
period. Suggesting some as yet hidden common factor. Clearly our Sun
is variable. We have had clues before, notably from the 1645 to 1715
AD Maunder Minimum , when no sunspots were seen, and the early 12th
century Millenial maximum when there was a peak in solar activity, and
warm conditions on the earth. All of which solar activity increase,
concerns radio users. Whereby We have had several peak solar activity
cycles in the last 60 years and no shortage of Auroras. 

So what can we expect as we rapidly approach the next sunspot cycle
maximum. All bets are off presently as the Sun is nowhere near as
active as it was 10 years ago. But hopefully this will change and the
coming winter 1999/2000 will provide plenty of good DX on 10m and 6m 
plus lots of HF satellite sub horizon DX. Unfortunately we can also
anticipate a considerable rise in the density of the upper atmosphere
as we go to sunspot maximum. In previous cycles this has produced much
more drag on satellites orbiting below 1800 kms. With the lower
altitude circa 700 kms high amsats being worst affected and needing 
fresh keplerian orbital elements ever two months or so, while Mir and
the ISS will suffer even more with marked non linear changes in orbit 
Then beyond the sunspot peak as the activity starts to decline we can
expect an even bigger than usual number of radio auroras. Now that 
Ulysees and other observations have revealed that this auroral peak
post sunspot peak occurs because the coronal holes which produce these
disturbances are no longer at high solar latitude firing out of the
ecliptic, but are at low solar latitude firing almost directly at us.