A ring of light will appear around the ball as the outer rim of the lamp comes into view. At some point, the basketball will appear smaller than the lamp. However, as you move away from the ball, its apparent size decreases. You are within the umbra, and the lamp is invisible. As long as you are fairly close to it, the ball's apparent size exceeds the lamp's apparent size. Imagine once more that you are looking at the lamp from behind the ball. In this experiment, the light source is another round lamp, but this time it has twice the ball's diameter. Rule: If the diameter of the light source is larger than the diameter of the object, a 3rd type of shadow appears where the cone-shaped umbra ends: the antumbra. If the diameter of the light source exceeds that of the object, an antumbra appears. ![]() You are standing on the side of the ball exactly opposite to the light source, facing it, so the order is: light source – basketball – you. Both the light source and the basketball are at the same height as your head. So imagine that you are in a windowless room with 1 light source and 1 round object that casts a shadow, say, a basketball. However, their absolute size is irrelevant, so a basketball illuminated by a large lamp produces the same shadows as the Moon illuminated by the Sun. The number and types of shadows created by an opaque object depend on its size in relation to the size of the light source. To understand why the Earth and the Moon have 3 types of shadows, let's start on a smaller scale. The umbra is the shadow's dark center portion, while the penumbra and the antumbra are different types of half-shadows. The type of eclipse we experience depends on the type of shadow that is involved. A solar eclipse may be total, partial, or annular a lunar eclipse may be total, partial, or penumbral. However, there are different types of solar and lunar eclipses. ![]() If the Moon's shadow falls on Earth, we get to see a solar eclipse the Earth's shadow falling on the Moon results in a lunar eclipse. ![]() The Moon's umbra, penumbra, and antumbra. Business Date to Date (exclude holidays).
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