Friday 4 September 2015

Our Wonderful Sun

Hello all,

I’ve been able to steal a few moments over the last couple of weeks to sketch Sol.

This is turning into a wonderful journey for me with the Sun.  I am not just marvelling at its ever changing surface.  It has also spurred me onto learning about our parent star.  I never thought nuclear fusion could be such a spectacular topic!!!

August 18 gave me a very active limb and chromosphere quarter section.  The chromosphere (surface of the Sun) was riddled with fine filaments (prominences seen over the surface), plages and sunspots.  The limb had an assortment of prominence types – arch, platform arches, & a pyramid.  Also a lovely long spicule.

Yesterday was a race to beat the approaching clouds and rain.  The race became more intense as the Sun had two wonderful areas of activity on the go, but on opposite sides of the disk.  As things turned out, I was only able to complete only one of the two sketches I hoped to accomplish.  Better something than nothing…

The second sketch presented here shows two different stages of prominence development.  The brighter part on the lower right shows mature platform prominences.  They are called platform as they exhibit a flat, table like roof where high energy plasma is racing through the magnetic fields on the surface of the Sun.  There are two platform prominences here, with a smaller & brighter one underneath the taller but thinner one above it.  The larger top prominence stretched out into an ever diminishing ribbon, to then frazzle out into shredded pieces.  A really lovely spectacle to follow through off fine details.

Plasma, for folks who may not be familiar, is a gas that has been heated to such a high temperature that its outter layer of an electron (in the case of Hydrogen) or electrons (for Helium), have been ripped off.  The result is a gas that is electrically charged, and so is affected by the strong magnetic fields that develop on the Sun’s hot surface.  These magnetic fields channel these plasma gases through what we see as tube like arches – prominences!  These magnetic fields are not stable and permanent features on the Sun, appearing and disappearing all the time, that can last between hours through to weeks.  And as these magnetic fields fluctuate, the prominences change in shape.

Large prominences, when they finally collapse, can create magnificent and enormous plume of plasma that billow out from the sun out into space.  We commonly know these as flares.  I’ll describe how these flares manifest themselves here on Earth another time, and how they can knock out electrical networks.

But be they large or smaller prominences, when they do collapse, the material that is released is known as a Coronal Mass Ejection (CME).  There is an intermediate step in prominence evolution, but we’ll deal with these later when I am able to sketch on of these.

It is the disintegrating stages of one of these coronal mass ejections that we see on the upper left.  We see just the remaining columns of plasma that is being held in place by the weakening magnetic fields.  When I started this sketch I had been able to spot some of the plume of escaping plasma being launched off into space.  I should have sketched this section first, rather than the platform prominences, for when I returned to the CME, that plume was too faint to see through the incoming thin cloud.  Oh, well, lesson learnt…

Both sketches were done using the same equipment:
Scope:  ED80 f7.5 refractor
Gear:  Daystar Quark, 25mm plossl, 101X
Dates:  18th August & 3rd September, 2015

Location:  Sydney, Australia.

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