Dear Petra, thank you for your very nice question.
I don't have a very good or specific answer for you, but here's what I would say from the top of my mind.
The way to think about this, is to not think of the physical material planets, Sun and Moon, in their orbits, but to use and firstly imagine the model of the celestial planetary spheres (see Schema FMC00.536) whereby the spheres interpenetrate and are embedded in one another like the russian dolls. That is how the influences of all these 'planets' or better planetary spheres (including sun and moon, then), are always here on Earth, also. This is a fundamental element of the spiritual scientific worldview, as coined in the concept of the Golden Chain were these influences ripple down from the cosmos, and the kingdoms of nature on Earth are under continuous influences of these influences of planets and stars and zodiac. These influences are etheric formative forces, we should not imagine it materialistically.
Now when we see that a planet is in front of a zodiac sign, it modulates this influence (explained ao here: Zodiac#1924-05-17-GA353). So influences can be weakened or strengthened , imagine wavefronts that can resonate depending on the frequency.
In a similar way, when conjunctions occur, there is an alignment between the planets and the combined effects of the spheres and thus their influences. There are drawings were Rudolf Steiner gave examples of such planetary line-ups, I could look it up if you want.
For me eclipses have to be imagined in the same way as in the descriptions above. This is also why the ancients paid such importance to conjunctions and eclipses. They were not concerned with these remote little lights of physical material bodies in the sky, so very far away, that we imagine in our current astronomy .. that is a very materialistic, and erroneous paradigm. Rudolf Steiner explains this nicely when describing the true nature of astrology and astrosophy, see topic page on astrology. However just as WIFI/4G is not visible but still there all around us, the same applies to spiritual influences .. our current consciousness is like a bandpass filter. Clairvoyant faculties are needed to study these influences in a direct way .. though we can observe their effects in an indirect way, of course, eg in alchemy or just the changing seasons, plant growth, etc.
To conclude, a lateral thought on 'shielding sun rays'. In previous cultural ages the druid priests used granite monoliths to also block the sunrays and be able to 'read the shadow', and similarly tumulus hills. (see here for illustrations - explanations are on the topic page). There's also the term 'seeing the sun at midnight'. All these relate to clairvoyant observation of the supersensible influences, we're talking about modulated astral effects here.
So though it wasn't a direct answer, I still hope the above is useful food for thought. Rudolf Steiner's descriptions of the eclipses have to be interpreted as clairvoyant observations of the influences, not just how we think about sunrays or light that is blocked.
We can continue and go into further into it, if you like, just wanted to acknowledge your question with a first reaction.
