Solar Eclipse: Length of the Umbra & Earth-Moon Distance

The distances to the Sun and the Moon are 149,600,000 km and 384,400 km. These figures are average values, and the actual values are around these averages. In a solar eclipse, the actual distances determine whether a total or annular solar eclipse occurs.

Flat-Earthers calculated the geometry of a solar eclipse using these average distances and discovered the umbra does not reach Earth’s surface. They wrongly concluded that an eclipse should not occur. In reality, the numbers are only averages, not the real values. And if the umbra does not reach Earth’s surface, it will still produce an annular solar eclipse.

Earth’s orbit around the sun is an ellipse with the sun lies in one of its focal points. As a result, the Earth-Sun distance varies, and the figure of 149,600,000 km is only the average. The actual value lies between 147,100,000 and 152,100,000.

It also applies to Earth-Moon distance. The figure of 384,400 km we often hear are just the average distance. And the real value lies between 356,400 km and 406,700 km.

The variation of these distances causes the fact that sometimes a total eclipse occurs, and sometimes an annular eclipse occurs. If the umbra reaches Earth, then a total solar eclipse occurs. If not, then an annular eclipse occurs. If the length of the umbra is almost the same as the Earth-Moon distance, then a hybrid eclipse occurs, where a total eclipse occurs in some locations in the eclipse’s path, and an annular eclipse in the rest of the locations.

Everything is consistent with our understanding that Earth is a sphere, and it is impossible to explain using the flat Earth model.