Largest Sun Spot In Nine Years Now Viewable

Mazarin writes: "The BBC has an interesting article about the largest sun spot to come around in nine years. 'The spot, which is moving towards the centre of the Sun's disk, covers an area a dozen times larger than the entire surface of the Earth.' The article goes on to talk about other sun spots that have caused minor disturbances and gives a nice little warning about not looking at the sun during this time."

Comments

Sunspot info site

[Twid]

Although it's geared towards kids in school, NASA has a great site on Sunspots here.

There is also an interesting article on the recent coronal mass ejection here.

Also read about the cold summer of 1816 here. It is theorized that the earth was extra cool because of sunspot activity.

Fun stuff... brings out the amateur scientist in me.

-Todd

Feynman says...

[rjh]

In Surely You're Joking, Mr. Feynman! (are there two Ns or just one in his name? I always forget), Richard Feynman talks about the Trinity nuclear test. He was the only person to look at the nuclear bomb directly, and suffered no permanent eye damage.

According to Feynman (or at least, what's written in his book), it's the ultraviolet light which cooks your retinas, and that visible light simply won't do it no matter how intense it is. He took the simple precaution of watching the nuclear blast through a truck windshield, which is UV-opaque. While he had a big purple blotch in his visual field for several minutes afterwards, he did manage to watch a nuclear blast without permanent damage, which I think is pretty damn cool. :)

From my own experience, I can submit anecdotal evidence which supports Feynman's UV-is-the-problem hypothesis. Once, while working in a laser holography lab, I wound up getting an eyeful of HeNe. While I was damn near blind in that eye for ten minutes afterwards, I had no permanent effects.

ObWarning: I am not a competent eyecare professional, and don't try either of these stunts at home. Really. Especially not the nuclear one. :)

Re:Feynman says...

[deglr6328]

i'm betting those HeNe tubes were less than 5 milliwatts though. IMHO saying visible light simply won't damage your eyes no matter how intense it is, is just plain false.

the energy of a laser beam can be intensified up to 100,000 times by the focusing action of the eye. If the irradiance entering the eye is 1 mW/cm2, the irradiance at the retina will be 100 W/cm2.

so if you have anything over 30mW, no matter what wavelength(except far ultraviolet and mid to far infrared which will cause burns to the cornea) in a direct beam impact of the eye you are almost absolutely sure deposit enough energy in your retina to cause fast heating and burn even considering the blink reflex.

kinda

[Uberminky]

Amateur radio operators ("hams") will be familiar with this.. Basically, when there's more sunspots, the upper atmosphere is ionized more than usual. This makes sky-wave propagation (radio waves bouncing off the upper atmosphere, usually in the F2 region) much better because it defracts more. Makes it easier for the radio waves to bounce off of the upper atmosphere. So in times when there are lots of sunspots, DXing (talking long distance) is better. Of course this is basically only relevant during the day, because at night the ions created by the UV from the sun combine with the free electrons and neutralize (and are this no longer ions). Everyone feel free to rip this to pieces, I'm still studying for my ham radio exam.. ;)

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