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Author Topic: Why Are Sunspots Black ?  (Read 7425 times)

Offline neilep

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Why Are Sunspots Black ?
« on: 31/08/2007 16:32:32 »
Dear Sun Spot Spotters,

Here is a Sunspot and some how Earth got in the way as I took the photo !
Typical of Earth !!...such a poser !! :)...well..as you've probably guessed the piccy is designed to indicate how big a sunspot is compared to Earth!



Question time !

How hot is a sun spot ? How long do individual sunspots last ?
How hot is the surface of the Sun ?
Surely sun spots are still hot enough to radiate light aren't they ?..because I am surprised how black they are !!..does this mean I could survive inside one/on one ?

Whajafink ?

« Last Edit: 31/08/2007 17:14:56 by neilep »


 

Offline eric l

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Why Are Sunspots Black ?
« Reply #1 on: 31/08/2007 16:55:15 »
Compare it with an other situation :  look at a picture of an erupting volcano, with a red flow of lava. 
If you ever come near an active volcano, probably you will not see a red flow of lava, but a grey flow with a red spot here and there, very much like dying embers.  But the photographer takes the picture at dusk or at down, with little ambient light, so that he can work at long exposures ("long" being 1 second or longer).  Because there is little contrast between the intensity of the light emitted by the lava and the ambient light illuminating the surroundings, you will see both in the picture.
If you would take a picture of the sun with an exposure long enough to see the colour of the sunspots, the surrounding parts (shown fiery red to orange) would appear blurry white; overexposure might even damage the equipment.
If you want to photograph the colour of the sunspots, you have to install some mask hiding the rest before making the picture; you can also do the opposite in your darkroom when making a print from the negative :  mask the spot and expose the rest for a longer time.  (In our amateur photographers club we learned to do so when we had pictures with too much backlight)
 

Offline Soul Surfer

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Why Are Sunspots Black ?
« Reply #2 on: 31/08/2007 18:32:50 »
Sunspots are infact quite bright but because they are a bit cooler they look a bit dull compared with the rest if the sun
 

Offline neilep

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Why Are Sunspots Black ?
« Reply #3 on: 31/08/2007 23:44:42 »
THANK YOU ERIC and IAN,

I wish they would say this when they show you pictures of sunspots on TV !

Also, many many times when they show film of sun flares exploding and then being then being pulled back in by gravity...are they in real time or not ?...the same with the aurora Borealis ?
 

Offline Soul Surfer

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Why Are Sunspots Black ?
« Reply #4 on: 02/09/2007 09:21:10 »
I do not think that dynamic shots of solar granulation and large prominances are in real time. They are time lapse shots like moving cloud pictures taking several hours to develop.
 

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Why Are Sunspots Black ?
« Reply #4 on: 02/09/2007 09:21:10 »

 

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