How far from the Sun must you be to look at it?

[Leovinus]

If you look at the Sun from Earth, you go blind. If you look at it from the nearest start it's a pretty white dot. Somewhere in between is the distance where you can look at the Sun and not go blind. Is that point within our solar system? <div class="Discussion_UserSignature"> </div>

 

[qzzq]

I don't know where it is exactly, but once you get passed Jupiter, I expect it would be possible to look into the Sun directly. From way out, say Pluto's quircky orbit, the Sun just looks like a bright star, so it's well inside the Solar System. <div class="Discussion_UserSignature"> <p> </p><p>***</p> </div>

 

[CalliArcale]

<blockquote><font class="small">In reply to:</font><hr /><p>If you look at the Sun from Earth, you go blind.<p><hr /></p></p></blockquote><br /><br />Actually, that's not entirely true. You can look straight at the sun with the naked eye for more than a few seconds and suffer no permanent damage to your eyes. (You may experience considerable discomfort during the experience, and afterwards you may suffer bleaching of the cells in your retinas, conceiveably enough to cause limited blindness, if you had the stamina to look long enough. But they will recover completely, especially if you use dark therapy and confine yourself to pitch-black rooms for a few days. This actually happened to Newton.)<br /><br />A telescope can magnify the heat of the sun enough to rapidly and permanently damage your eyes. And during a partial eclipse, you can suffer damage to your retinas because the normal mechanisms that reduce the exposure to a safe level (pain, contraction of the irises) are tricked by the darker sky and let in too much.<br /><br />So strictly speaking, you can look at the Sun from *Earth* and not go blind. <div class="Discussion_UserSignature"> <p> </p><p><font color="#666699"><em>"People assume that time is a strict progression of cause to effect, but actually from a non-linear, non-subjective viewpoint it's more like a big ball of wibbly wobbly . . . timey wimey . . . stuff."</em>  -- The Tenth Doctor, "Blink"</font></p> </div>

 

[Leovinus]

I was referring to the ability to stare as long as you want at a star in the sky without going blind. This can't be done with the Sun from here. <div class="Discussion_UserSignature"> </div>

 

[zavvy]

I must be weird because I used to stare at the Sun a LOT when I was a child. I never went blind and have always had 20/10 vision..<br /><br />I do have a few vitreous floaters that never seem to disappear though...

 

[Maddad]

Just look at it at night and you won't go blind.

 

[dark_energy]

Wait, wait, wait.....there's 20/10 vision?! <div class="Discussion_UserSignature"> </div>

 

[Leovinus]

Well I used to have 20-18, so I suppose someone could have 20-10 if they have *really* good eyesight. <div class="Discussion_UserSignature"> </div>

 

[dark_energy]

I currently have 20/18. <div class="Discussion_UserSignature"> </div>

 

[spacester]

I used to have "better then 20/10" vision<br /><br />I'm probably down to about 20/20 now . . .<br /><br />Sigh . . . <div class="Discussion_UserSignature"> </div>

 

[CalliArcale]

But you won't go blind, which is what I was referring to. You're right that I shouldn't have said "no permanent damage" -- I meant and should've said "no permanent blindness". Leo was asking about looking at the sun without going blind.<br /><br />Basically, trust in the pain sensation. If it hurts to do something, don't do it. Your eye will tell you when something is too bright, and it is likely that this response evolved to keep us from looking at the Sun too long. To look at the Sun long enough to do significant long-term damage, you need extraordinary pain tolerance -- or you need to be looking at it during an eclipse, when your natural defense mechanisms will be fooled.<br /><br />There's a website that has a good article on the subject, going into the physiognomy of the situation:<br /><br />Galileo, solar observing, and eye safety<br /><br />It's very interesting. Some of the more interesting points:<br />* eye damage is almost never thermal; it's photochemical<br />* the dangerous wavelength under normal circumstances is neither IR nor UV; it's actually visible<br />* some people seem to be much more prone to damage than others, but there's no way to know who it is until they've had their eyes permanently damaged<br />* sunlight appears to be much more dangerous in the afternoon than at high noon; this is likely because the atmosphere is reducing the total brilliance of the sun but not filtering the dangerous wavelengths as much<br />* immediately before sunset (this page suggests one solar diameter or less above the horizon), the Sun becomes reasonably safe for viewing because of how much light is attenuated by its passage through the atmosphere<br />* abnormal dilation of the pupil greatly increases your chances of solar retinopathy; note that many over-the-counter drugs can produce dilated pupils<br /><br />Nevertheless, I also don't advise staring at the sun for prolonged periods. You will <div class="Discussion_UserSignature"> <p> </p><p><font color="#666699"><em>"People assume that time is a strict progression of cause to effect, but actually from a non-linear, non-subjective viewpoint it's more like a big ball of wibbly wobbly . . . timey wimey . . . stuff."</em>  -- The Tenth Doctor, "Blink"</font></p> </div>

 

[Leovinus]

It's no wonder that early cultures treated the Sun as a god. Look right at it and you fry. If you don't have it, you freeze and your plants and animals die. You have to respect its power. <div class="Discussion_UserSignature"> </div>

 

[CalliArcale]

The Egyptians had an interesting variation on the widespread "all-powerful god sends wrathful devastation to punish humanity, but then decides to let some live after all" myths. Their story was that Ra (the sun god) became angry with the world and decided to wipe out humanity, so he sent his Eye (the Sun, also the lion-headed goddess Sekhmet) into the world to cleanse it with fire. At the last minute, he decided to recall her and let some live. <div class="Discussion_UserSignature"> <p> </p><p><font color="#666699"><em>"People assume that time is a strict progression of cause to effect, but actually from a non-linear, non-subjective viewpoint it's more like a big ball of wibbly wobbly . . . timey wimey . . . stuff."</em>  -- The Tenth Doctor, "Blink"</font></p> </div>

 

[kmarinas86]

I looked at the sun, but only when its dark red... <img src="/images/icons/tongue.gif" />

 

[CalliArcale]

<blockquote><font class="small">In reply to:</font><hr /><p> Don't say this to the surgeons. You'd lose lots of friends. THIS is an<br /> important exception. And many times, 'no pain no gain' is a real fact.<br /> But there's little to be gained by going blind.<br /> Reminds me of the joke. Man walks into his doc's office and says, "Doc<br /> when I **** my head to the right like this, it hurts. What should I do<br /> about it?"<br /> Doc: "Don't **** your head to the right!"<br /> My humorous way of agreeing with you.<p><hr /></p></p></blockquote><br /><br />My dad tells that joke all the time. And he's a doctor. <img src="/images/icons/wink.gif" /> He's also a certified trauma surgeon, and he agrees that pain is often a good indicator of damage, and you should pay attention to it.<br /><br />Actually, I have a lot of surgeons in the family. My uncle, for instance, harvests kidneys from brain-dead patients.<br /> <div class="Discussion_UserSignature"> <p> </p><p><font color="#666699"><em>"People assume that time is a strict progression of cause to effect, but actually from a non-linear, non-subjective viewpoint it's more like a big ball of wibbly wobbly . . . timey wimey . . . stuff."</em>  -- The Tenth Doctor, "Blink"</font></p> </div>

 

[CalliArcale]

<blockquote><font class="small">In reply to:</font><hr /><p>Yours is a very interesting observation about what happens when there are huge amounts of dust and smoke in the atmosphere. Earlier last month, there were huge fires near sacramento. The Sun, all Day long was Red-Orange, very red and it was NOT bright, either. I have never seen such a thing in 50 years of memories.<p><hr /></p></p></blockquote><br /><br />Wild, isn't it? We almost never get that here, where the winds come from the plains which seldom burn these days (it's all farmland), but when Yellowstone burned, the sun was blood-red here in Minnesota for a couple of days. Very spooky.<br /> <div class="Discussion_UserSignature"> <p> </p><p><font color="#666699"><em>"People assume that time is a strict progression of cause to effect, but actually from a non-linear, non-subjective viewpoint it's more like a big ball of wibbly wobbly . . . timey wimey . . . stuff."</em>  -- The Tenth Doctor, "Blink"</font></p> </div>

 

[iron_sun_254]

I wouldn't suggest staring at the Sun for too long even if it's dim and red. Things that block visible light do not necessarily block UV light and damage can still occur even if you don't feel it.

 

[5stone10]

<font color="yellow">stevehw33 -> "Yours is a very interesting observation about what happens when there are huge amounts of dust and smoke in the atmosphere. Earlier last month, there were huge fires near sacramento. The Sun, all Day long was Red-Orange, very red and it was NOT bright, either. I have never seen such a thing in 50 years of memories."</font><br /><br /><br /><br />This phenomena you describe gave me a decent idea of what a nuclear winter would be like. It was amazing - and extended from the Sierra Nevada foothills almost all the way to the Bay area.<br /><br />There was another wild fire near Sonoma in addition to the ones near Placerville.

 

[wisefool]

During the recent Venus transit our group was atop a nearby mountain, with heavy fog and clouds in the valley reaching a few degrees above our horizon. When Venus rose above the horizon the transit was already underway. As the clouds barely started to thin out we could briefly look at the Sun and see at zero magnification the disk of Venus. At all other times we used appropriate sun filters.

 

[wisefool]

For what it's worth, the Sun is classified as a dwarf main sequence star. It is bright to us, but that's because it's only eight minutes away as light goes. Put it out 10 parsecs, about 32 light years away, and you get its so-called absolute magnitude, which is roughly that of a very dim 5th magnitude star. <br /><br />The "dome" above us looks 2-D, but is of course 3-D. Some stars which are very bright, such as Sirius, are so primarily because they are nearby. Others are much brighter, but farther away. An interesting contrast is Sirius at -1.4 magnitude, which makes it the brightest true star, but which is about eight light years away, very close. In contrast, Orion's brightest star, Rigel, is just over zero magnitude -- and it's 1,500 light years away. Imagine how bright Rigel would be if it were 10 parsecs away, or just eight light years away.

 

[Leovinus]

Or 8 light minutes away. <div class="Discussion_UserSignature"> </div>

 

[grooble]

mmm bacon. I remember a guy getting a grub embedded in his head, he had to leave a rasher of bacon on his head for 5 days to get it out.

 

[wisefool]

If I'm not mistaken, Rigel being a supergiant blue star, we might be inside the star itself. Also, the surface temperature is several times hotter than the hottest skillet. So, instead of being fried bacon, we would be instantly vaporized "bacon."