APOD: Orange Sun Scintillating (2011 Nov 15)

[BMAONE23]

It would be interesting to see a 4 layer roll over image showing
L1) Visible light image
L2) H alpha image
L3) Inverted H alpha
L4) Colorized final image
using 4 adjacent squares in a lower corner to initiate the roll over

[BMAONE23]

Anyone else notice the two spots that resemble the mandelbrot set?

Well... I was going to say I saw a duckie and a horsie, but I changed my mind.

What I noticed is that in the high res image within the sunspot group AR 1339 there is an owl visible next to the largest spot

[zloq]

I appreciate that the image is an inverted H-alpha image but nevertheless, to me, "The gradual brightening towards the Sun's edges is caused by increased absorption of relatively cool solar gas and called limb darkening" sentence is still very confusing. The information brought up through the "limb darkening" link is helpful though the illustration there does shows limb darkening unlike the APOD which is brightening to the edge!

I think the fact that everyone gets tongue tied describing the physics of what's happening in the context of the image means it isn't ideal for communicating what H-alpha tells you about the sun. Even if the image were a simple inversion of brightness it is confusing to call the bright limb a dark one. But the killer for me is that selected features have been specifically altered - which means any talk of "cooler" plasma either by the caption or Phil Plait is going to get in trouble - since the cool sunspots are specifically altered to show as pleasingly dark despite the inversion.

I think the selective alteration of features puts this image in the category of artistic interpretations fairly decoupled from the data and the physics involved. You could use it to get people excited about cool stuff happening on the sun that looks kinda like that - but beyond that I don't think it works well to convey insights from H-alpha solar imaging - especially if this alteration isn't mentioned or even known by people describing the image.

zloq

[DavidLeodis]

I appreciate that the image is an inverted H-alpha image but nevertheless, to me, "The gradual brightening towards the Sun's edges is caused by increased absorption of relatively cool solar gas and called limb darkening" sentence is still very confusing. The information brought up through the "limb darkening" link is helpful though the illustration there does shows limb darkening unlike the APOD which is brightening to the edge!

It seems logical that if you an invert an image of the Sun, the limb darkening becomes "limb brightening". Are you finding the concept of limb darkening confusing, or just the use of "darkening" when that isn't what the image appears to show?

The latter. To cut the sentence in question a bit short and highlighting some words to more clearly show what I mean in that it is confusing "The gradual brightening ...called limb darkening." The full sentence is, to me at least, very confusing in relation to the APOD image. It's a nice image though.