HOMETHE NEW MOON
Although it is close, big and relatively luminous (its magnitude reaches in fact a value of -3, i.e. 1.5 magnitudes more luminous than Sirius) the new Moon is probable one of the celestial objects least observed, both by amateurs and professional astronomers.
May be for this reason that I have always had the anxiety of taking a picture of the Moon in this phase: the result would have been a full Moon in the phase of new Moon!
It is certainly not an easy task. But it is nor impossible. It should not be forgotten that, at the moment of the new moon, an observer located at the Moon, as for example at the Sea of Tranquility, would see the Earth very high in the sky, with a diameter 3.67 times bigger, an area 13,45 times bigger, and, due to the greater albedo of the Earth, with a luminosity 71 times higher than that of the full Moon observed from the Earth. But, yes, it has been correctly understood: the glare of the Earth on the Moon is 71 times more intense than the glare of the Moon on the Earth. Why not trying to take a picture of it?
The best moment would evidently be a total Solar eclipse, specially if the shadow of the Moon is on the ocean, to avoid weakening the Earth’s luminosity.
And for this reason, on November 3, 1994 I went to Iguazú Falls taking a 1000 ASA film. The Ektar 1000 was certainly not the film best fit for a total eclipse, but I really wanted to take pictures of the Moon’s seas.
Unfortunately, I did not quite properly appraise the difficulty, and, even with exposure times 30 times longer than necessary for the Corona, the result was null !!
Nevertheless, I have considered it appropriate to mention this intent in the Swiss magazine ORION (number 268, June 1995, page 142).
The following year, another well-known amateur made the same attempt, but with also modest results.
Not until 1998, on the occasion of another total Solar eclipse (February 26 in the Caribbean) Christian Viladrich could finally imprint on a photo the Moon’s seas at the moment of totality.
Though the photograph is spectacular, the result was attained … by accident !!! Viladrich’s intention was not in fact to take a picture of the seas, but to make evident the finest details of the Corona. Nevertheless, it was demonstrated that this was feasible.
Personally, I support the idea that it is possible to obtain even much better results. Eclipses in the future will be many, and with them more possibilities of attaining a good result.
But, is it necessary to wait for eclipses? The Hubble is still in orbit, and also the alternative of the coronograph: Bernard Lyot invented it almost 80 years ago. Why not trying - with an adaptor, if necessary - to focus it once to the new Moon, and try to see more clearly how the glare of the Earth is up there?
A proposal for the professionals, if we want to; with the hope that among them there might be a black sheep that does not consider this experience as a loss of time.
In the meantime, we could try to get trained taking pictures of the ash-grey light of the Moon when it is a few hours old.
Making calculations a posteriori, it resulted in:
- the new Moon is about 7500 times less brilliant that the full Moon;
- the Corona is about 40 times less brilliant than the full Moon;
- the Corona/new Moon relation is then of 187:1.
If by the Corona - with 1000 ASA and 5.6 opening - an exposure time of 1/30 of a second
is correct, as it has been practically demonstrated, the time for the maria of the Moon should
then be 187 times longer, i.e., of about 6 seconds. Over-exposing the Corona, obviously.
But it should be easier than photographing the ashgray light of the Moon when it is two days
old, as the Corona is twice less brilliant than the Moon in this phase.