What the author of the email is pointing out is that: * A (total) solar eclipse is merely a statement that you, the observer, happen to be present in a small r

What the author of the email is pointing out is that: * A (total) solar eclipse is merely a statement that you, the observer, happen to be present in a small region of a few miles' radius, wherever the moon's shadow happens to be. If you imagine yourself flying around in space (or even just driving around in a car), you can very easily get out of this region and see that the sun continues to shine, etc. * A (total) lunar eclipse is a statement that the earth's shadow falls on the moon. No matter where you are in space, this is a statement about the amount of light reaching the moon's surface, independent of where the observer happens to be. You may not care about this, deciding that your vantage point as an observer is all that matters (whether your view of the sun or moon changes, respectively) by saying "Obviously eclipse is measured relative to the observer", but the author cares, and it's an interesting point. Obviously he's not claiming that a solar eclipse isn't "real" in the sense that you can't see it; only that it doesn't correspond to any astronomical event that is observer-independent (and relevant to more than a small region of the earth). Edit: Another way of saying this is that despite the name, a "solar" eclipse is a statement about (a small region of) the earth -- that's the part that gets less light; the sun is unaffected by a solar eclipse. On the other hand, a lunar eclipse is really a statement about the moon; the moon really does get less light during a lunar eclipse, as the moon is what is in shadow.