Paraphyletic

Medicine and human biology
Venus is making a rare transit across the Sun tonight in the Americas, and tomorrow morning most everywhere else. To figure out when, enter your location here.
You can look directly at the spectacle. Or through spectacles. But I don’t recommend that.
First, looking directly at the Sun, you will not see Venus. Our star’s giant fission/fusion explosions produce such high intensity light that your rod cells get confused, and the visual noise will drown out something as subtle as a small black dot.
Second, cumulative exposure to direct sunlight can actually cause damage to your retina, and specifically to a small disc called the macula, which is where light usually gathers, where you focus the sharpest, and where you see best.
In other words, you can look at the Sun for a few seconds without causing irreversible damage to your eye. Just don’t do it very often.
For tips on safe viewing, see this video by “dark sky advocate” David Fuller.
Another myth people have about Sun-caused eye damage is that the Sun is actually burning the retina. It isn’t. Although the Sun is producing lots of different kinds of radiation — including visible light — it’s ultraviolet that’s causing the problems. UV isn’t burning you (or your skin, for that matter, even though it may feel like it). UV light is colliding with molecules in your cells, causing damaging chemical reactions that may or may not be fixable. If your retina is exposed to enough UV, your rod and cone cells will be damaged.
So as soon as the Transit of Venus is over, go back inside your house/dorm/apartment and tumblr. It’s good for your health.
You can always get your vitamin D from pills.

Venus is making a rare transit across the Sun tonight in the Americas, and tomorrow morning most everywhere else. To figure out when, enter your location here.

You can look directly at the spectacle. Or through spectacles. But I don’t recommend that.

First, looking directly at the Sun, you will not see Venus. Our star’s giant fission/fusion explosions produce such high intensity light that your rod cells get confused, and the visual noise will drown out something as subtle as a small black dot.

Second, cumulative exposure to direct sunlight can actually cause damage to your retina, and specifically to a small disc called the macula, which is where light usually gathers, where you focus the sharpest, and where you see best.

In other words, you can look at the Sun for a few seconds without causing irreversible damage to your eye. Just don’t do it very often.

For tips on safe viewing, see this video by “dark sky advocate” David Fuller.

Another myth people have about Sun-caused eye damage is that the Sun is actually burning the retina. It isn’t. Although the Sun is producing lots of different kinds of radiation — including visible light — it’s ultraviolet that’s causing the problems. UV isn’t burning you (or your skin, for that matter, even though it may feel like it). UV light is colliding with molecules in your cells, causing damaging chemical reactions that may or may not be fixable. If your retina is exposed to enough UV, your rod and cone cells will be damaged.

So as soon as the Transit of Venus is over, go back inside your house/dorm/apartment and tumblr. It’s good for your health.

You can always get your vitamin D from pills.

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