Solar Flares and Prominences

[Astronuc]

Solar flares are huge explosions on the surface of the sun, throwing out massive amount of material as matter is heated to millions of degrees in a few minutes. It can last from minutes to hours.

A Prominence is an elongated structure full of material hundreds of times cooler and denser than the surrounding corona. They are held up and insulated by huge magnetic structures and are seen as prominences at the edge of the sun against the black background of space. They can stay suspended above the photosphere for weeks and even months, but eventually become unstable. Surprisingly, rather then collapse at that point, they actually erupt!

from http://www.telescopesales.co.uk/gloss.htm

Often associated with flares and prominences, a coronal mass ejection (CME) is the release of a huge amount of coronal material - measured in billions of tons and travelling at supersonic speeds. When they head earthwards, they have damaged satellites on their way and when they get here they can cause massive surges of power on electrical transmission lines.

[Astronuc]

more piccies of flares 

[Astronuc]

Solar Prominences

[Astronuc]

From - http://www.solstation.com/stars/sol.htm

I found

[Charity]

That is just beautiful. Funny how something so beautiful can cause so much havoc to us on earth.

[Skyjim]

And, just to show what you can see in small amateur instruments with the right filters:



A friend took this through my solar rig last June at the Grand Canyon Star Party.  The image is not as good as what you see with your eye - much crisper and more contrast on the disk details - the granularity is fairly subtle in the full size version of this image, but it's obvious to the eye.  This is an example of the size of commonly seen prominences - look tiny but still a good 5 to 8 Earth diameters tall.

Jim

[yale]

Jim after using his solar telescope

[Astronuc]

Pretty cool picture Jim.  It's nice to have a homemade picture.

Have you even seen one of the CME's when it happened?

 

[Skyjim]

Well, Yale, I'd need TWO of those patches - I use a binoviewer.

The contrast gain vs monocular viewing is astounding!

Fortunately, my Coronado h-alpha filter is securely screwed into the lens cell of my refractor, and the front element is an energy rejection filter which effectively removes most of the the nastys even before the incoming sunlight passes through the etalon (0.8 angstrom bandpass interference filter centered on hydrogen-alpha at 656.28 nanometers).

Here's one reason I bought a Coronado - their transmission numbers are included from far IR to UV in their literature and independently verified...

http://www.coronadofilters.com/safety/halpha.htm

That, and the fact that the etalon and ER filter are front-mounted and extremely durable - unlike some other designs which put an ER out front, but require periodic replacement because the ER filter used significantly degrades over time.  (OUCH!)

Yale makes an important point though, for anyone out there fascinated by the prospect of solar observing.  If you are on a budget, the safest way to go is a projected white light image.  DO NOT attempt to cut corners on solar observing equipment and DO NOT assume a trusting attitude towards manufacturers and sellers of systems.  It's not that the market is rife with dangerous systems - it isn't, really - but poorly made, damaged, or carelessly used solar observing gear can cost you your eyesight!  NEVER use a solar filter that could fall or be knocked off a telescope, and NEVER use one which does not cover the aperture (the front end) of the telescope completely.  Check any filter for defects personally - a pinhole in a cheap filter is a prescription for disaster, and even high quality filters are subject to damage and degradation over time.  I advise emphatically to avoid used equipment.  KNOW your gear!

If this is more than you want to deal with, go to spaceweather.com and you can see lots of superb solar images at multiple wavelengths - scroll to the bottom of the spaceweather home page and you'll see lots.  I'm partial to the Big Bear Solar Observatory's "The Sun from Earth" page to get a quick look if I don't have time to set up my scope - or to check activity before heading off to show a bunch of school kids the sun in my equipment.

 Astronuc, unfortunately, I've never been in position to catch a CME.  Good thing SOHO does so well!

Jim

[yale]

And just to add to Jim's info...

Never, never, never, never use a solar viewer that consists solely of an eyepiece filter.

The energy MUST be rejected BEFORE it enters the scope.

A unshielded typical 8" scope would pump 30 watts of sunlight into your eyeball. Can you say hard-boiled egg?

So, echoing Jim's comments - either use a safe projection system or use only the highest quality, carefully installed and maintained direct viewing system.

[Astronuc]

And that 30 W would be concentrated in to about 1 mm² which is equivalent locally to 30 MW/m² - a lot of energy per unit area.

That's how magnifying glasses can burn or melt some materials!

[Skyjim]

The magnifying glass is the analogy I use to impress upon elementary school kids the nature of the risk.  All you need do is ask if they've ever seen a magnifying glass as you hold one up.  Then you look at a group of kids and ask if they've ever done anything to, say, ants with one in full sunlight.  I have yet to find a group that hasn't seen or personally performed this cruel little bit of hands-on science.  Sometimes, the fiirst hand up will be a girl - one never knows.  At that point, you simply explain that a telescope is just a fancy magnifying glass and that looking at the sun with an unfiltered scope or binos  makes your EYES the poor ant!

Generally the response is a variation of "EEEEUW!"  with a few "Cools!" thrown in by  daredevil types - but the point is made emphatically.

Jim

[Astronuc]

August and September have been particularly busy on the sun

There was a bouble flare and CME event (top picture) - August 22, 2005 - http://www.nasa.gov/vision/universe/watchtheskies/aug05_cme.html

A close-up of last Friday's flare (Sep 16, 2005) with the Transition Region and Coronal Explorer (TRACE) spacecraft (bottom picture). Credit: NASA/LMSAL.

For more information and movie downloads, see - http://www.nasa.gov/vision/universe/solarsystem/sept_aurora.html

[Astronuc]

Another flare, which I believe corresponds with one shown by Sky and Telescope.

[Astronuc]

Nick Strobel has an interesting picture showing the scale of the sun and planets.  But the interesting part is the huge prominence that he shows.  Jupiter would fit under the loop, and height to the outer edge of the prominence is about 2x the diameter of Jupiter.

http://www.astronomynotes.com/chapter1/s2.htm

http://www.astronomynotes.com/chapter1/sunplan.jpg

It is the same image but slightly different color shown in Reply #3 of this thread.  It was apparently taken from Skylab during the third and final mission in 1973.