Answer:
2
Explanation:
Though the effect of ships disappearing over the horizon <em>is </em>due to its spherical shape, it could also be used evidence for objects falling off the "edge" of a flat, planar-shaped earth.
Star brightness is defined by either <span>D. apparent magnitude - when we measure it from Earth (that is how bright it is from Earth) - this is the closest to "basic observation" and the best answer
or by absolute magnitute - how bright it would be at a certain distance (this allows to compare the brightness).
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