Bandwidth of light reflected from the Moon

[kinetic]

Hi all,

last night whilst using the 12" Newt visually on an 87% full moon
and widefield eyepiece I was astounded by the clarity.

(I should do more visiual with this big beast! :) )

It seemed to be such a good , contrasty view purely because the
image was sooooo bright and my eye was overwhelmed by the light.

I was , of course , dazzled in one eye for a good few minutes afterwards.

That made me think...exactly what bandwidth of light has made the
journey from the Sun....to the moon....to my aluminium coated mirrors...
through the eyepiece glass...to my eye?

Is it the full spectrum of what you get when you dare to look directly
at the Sun?
Or is it purely the visual spectrum?
Does the dark grey dust on the moon only let the visual reflect back?
Do the mirrors subtract a chunk of bandwidth?
What about Gamma rays and X rays etc?

It is something I have never thought of before.
Sorry if it sounds like a silly question.:rolleyes:

Steve

[mswhin63]

I agree it is a bright beast, essentially the bandwidth is the visible light spectrum and whatever can pass through the atmosphere in the infrared and ultraviolet. Ultraviolent would only pass through if there was a hole in the ozone above you but I think there is a very small amount that may come through.

You wouldn't need to worry about gamma and x-rays as these are blocked by our atmosphere so you wouldn't need to worry about exposure. I think gamma radiation would pass through the moon anyway x-rays would be the same.

As I use a 12" scope myself but I use Baader lenses I am able to attach a 2 inch double polarising filter in between the 2 and 1.25 inch adapter on the lens. I can now reduce the intensity of the moon to my eyes and I don't suffer from any of the over brightness issues after looking at the moon.

For a 12 inch scope I strongly recommend a double polarising filter if only just to save your dark adapted eyes.

[tlgerdes]

I dont know about total bandwidth Steve, but many people have taken photos of the moon and then hyperstaturated the picture to reveal colour reflected from the moons chemical composition.

http://apod.nasa.gov/apod/ap060907.html

[DavidU]

Here is a spectrum of the moon.

[Merlin66]

The reflected solar spectrum from the moon extends well into the infra Red. Infact some IR wavelengths are used to distinguish various types of rocks and surface conditions.

[Barrykgerdes]

The moon does not emit any visible light of its own.

Because it is not at absolute zero it will radiate and reflect infra red.

All light from the moon is reflected light from the Sun

The moon has an albedo of .12 so it reflects only 12% of the light it receives from the Sun

The harmful radiation from the Sun does not penetrate our atmosphere so any harmful reflection from the Moon would be even less likely to penetrate our atmosphere.

A spectrum from the reflected sunlight will be almost identical to the spectrum of the direct rays of the Sun and contain the same absorption bands. The most notable one is the sodium band in the yellow spectrum.

If you have a spectrometer you can see these absorption bands. Of interest if you do have one is to "burn" a small globule of salt in the gas flame you will see the emmision lines from the sodium in the same place as the absoption lines in the Sun's spectrum.

So to answer your initial question the bandwidth of the light reflected by the Moon will be essentially the same as that from the Sun but further attenuated because of the reflectivity of the moon.

We also know that the Moon reflects the much lower frequencies in the radio spectrum quite well.

Barry