A question on sunlight

[fireballxl5]

Was the intensity of sunlight known before Apollo 11, if so how was it measured.

The reason i ask is some HB has said Armstrong would never have lifted his visor (as in the new photograph) on the moon because it was unknown what would happen. I said he lifted the visor to help him see and not for a picture as the chap first thought.

I'm surprised Neil needed to raise his tinted visor to help him see. Wasn't the entire Tranquility Base environs bathed in reflected light from the lunar surface? It was certainly good enough light to fill in all the shadows for those wonderful photoes that have become modern icons .

Even if there was a visibility issue still seems fairly odd when you recall that we're dealing with unknown risks. Yes, there had been previous unmanned missions like the Luna and Surveyor ones etc, but still. This was humanity's first departure from the shields of Earth's magnetosphere. Wasn't Neil being a bit reckless?

Unless of course he wasn't beyond the Earth's magnetosphere. Maybe he wasn't beyond the border of the US State of Nevada!

Sorry if this is in the wrong section.

[gwiz]

It was know both theoretically (earth sunlight with atmospheric effect subtracted and moon reflection added) and by direct measurement from earlier unmanned probes.

[Ian Pearse]

Not sure what Earth's magnetosphere would have had to do with it. The magnetosphere affects charged particles, not the Sun's electromagnetic radiation, which constitutes the bulk of it's output, IIRC. So the experience of the Mercury and Gemini astronauts, as well as those of the previous Apollo's (esp. Apollo 8 and 10 as they went to the Moon too) would be relevant as benchmarks.

[drewid]

Visible solar radiation is about 30% stronger than a clear day at noon on the Earth's surface.

There's a thread here but it needs more investigation for better figures.

I'll have another rummage later.

[fireballxl5]

Thanks a lot chaps.

As the typical HB normally does after finding out the sunlight intensity was known he expanded his claim. Hes now saying they might have known the parameters but Armstrong was still the first man to lift his visor on the Moon and that makes it reckless and dangerous as they didn't know what would happen lol.

[Ian Pearse]

Jul 24, 2009 6:07:21 GMT -4 fireballxl5 said:

Thanks a lot chaps.

As the typical HB normally does after finding out the sunlight intensity was known he expanded his claim. Hes now saying they might have known the parameters but Armstrong was still the first man to lift his visor on the Moon and that makes it reckless and dangerous as they didn't know what would happen lol.

Given that they knew the parameters, does it not follow that they would design the helmet layers accordingly? Doesn't it also follow that, if they knew there would be a danger, they would either a) tell the astronauts not to lift their visors at all, or b) make the visors fixed and not moveable?

edit for typo

[drewid]

Lexan is opaque to UV, Eyes aren't bothered by infra red, visible frequencies aren't _that_ much brighter. He might have to screw his eyes up a bit but not really a risk.

[fireballxl5]

Jul 24, 2009 8:08:30 GMT -4 drewid said:

Lexan is opaque to UV, Eyes aren't bothered by infra red, visible frequencies aren't _that_ much brighter. He might have to screw his eyes up a bit but not really a risk.

I forgot about that and have just mentioned it. Heres what i got back:

Is it? :shock: :? It's opaque to UV but transparent to visible light? Remarkable. Especially as it must have also been opaque to rays just below visible light on the spectrum too. The IR must have been pretty powerful without an atmosphere when the daylight-exposed temperature on the moon was said to be close to 80 degrees C, or 200 degrees F!

Lexan would be a good material to make car windows out of. The terrible accidents where dogs roast in cars on sunny days would no longer happen. Why is not more commonly in use. :? :wink:

[Ian Pearse]

Tell your HB contact to do some research on the output of the Sun, and how much of it is and is not affected by passage through hte Earth'd atmosphere. And by research, I don't mean Youtube videos

[fireballxl5]

Lexan would be a good material to make car windows out of. The terrible accidents where dogs roast in cars on sunny days would no longer happen. Why is not more commonly in use. :? :wink:

Does blocking out the UV block out the heat??? Sorry for being a bit thick.

[blackstar]

If your friend finds the properties of Lexan so miraculous ask him if he has every managed to get a tan indoors, window glass/car glass also blocks UV while letting visible light through, and so it isn't the UV that's responsible for the unfortunate dogs.
Try the following link on your friend:

www.britannica.com/EBchecked/topic/1426115/industrial-glass/76330/Optical-properties

The heating effect inside the car is the notorious 'greenhouse effect' with glass taking the place of the upper atmosphere, which is of course why the call it the greenhouse effect in the first place!

[fireballxl5]

Jul 26, 2009 7:53:54 GMT -4 blackstar said:

If your friend finds the properties of Lexan so miraculous ask him if he has every managed to get a tan indoors, window glass/car glass also blocks UV while letting visible light through, and so it isn't the UV that's responsible for the unfortunate dogs.
Try the following link on your friend:

www.britannica.com/EBchecked/topic/1426115/industrial-glass/76330/Optical-properties

The heating effect inside the car is the notorious 'greenhouse effect' with glass taking the place of the upper atmosphere, which is of course why the call it the greenhouse effect in the first place!

Sorry I'm a bit slow on the itake but may i ask would using lexan car windows stop it getting hot inside like he thinks it would?

[blackstar]

Jul 26, 2009 8:10:59 GMT -4 fireballxl5 said:

Jul 26, 2009 7:53:54 GMT -4 blackstar said:

If your friend finds the properties of Lexan so miraculous ask him if he has every managed to get a tan indoors, window glass/car glass also blocks UV while letting visible light through, and so it isn't the UV that's responsible for the unfortunate dogs.
Try the following link on your friend:

www.britannica.com/EBchecked/topic/1426115/industrial-glass/76330/Optical-properties

The heating effect inside the car is the notorious 'greenhouse effect' with glass taking the place of the upper atmosphere, which is of course why the call it the greenhouse effect in the first place!

Sorry I'm a bit slow on the itake but may i ask would using lexan car windows stop it getting hot inside like he thinks it would?

He erroneously assumes that it is UV light that causes the heating, glass already blocks UV so it wouldn't make any difference.

[drewid]

Jul 26, 2009 7:40:36 GMT -4 fireballxl5 said:

Lexan would be a good material to make car windows out of. The terrible accidents where dogs roast in cars on sunny days would no longer happen. Why is not more commonly in use. :? :wink:

Does blocking out the UV block out the heat??? Sorry for being a bit thick.

No it doesn't IR is "hotter"

[fireballxl5]

So did the intense unhindered IR rays coming straight through the astronauts' visors have no adverse effects on the wearer? :? Seems hard to believe. To heat something to 80 degrees C it'd be like having your face next to an electric grill!

This is starting to make my head hurt lol.

I told him using Lexan for car windows wouldn't stop the car getting hotter and now Ive found the inner visor did block IR also.