The Moon is an celestial body that orbits planet Earth, being it′s only permanent natural satellite. It is the fifth-largest natural satellite in the Solar System, and the largest among planetary satellites relative to the size of the planet that it orbits (its primary). Following Jupiter's satellite Io, the Moon is second-densest satellite among those whose densities are known.

The average distance of the Moon from the Earth is 238,856 mi (384,402 km), which is 1.28 light-seconds away. However, the distance between the Moon and Earth varies because it′s orbit is elliptical. The two extreme points of the Moon’s orbit each month are known as the lunar apogee and perigee. When the moon is the farthest away (apogee), it is 252,088 miles away from the Earth. When at it's closest position (perigee), the moon is 225,623 miles away from the Earth.

Also, the Moon at apogee is 11% farther from Earth than it is at perigee. When at apogee, the moon is far enough from the Earth, that it cannot entirely block the bright light from the Sun, so any eclipses which occur near the moon′s apogee are not total eclipses, but instead, are annular eclipses.

The Sun happens to be 400 times the Moon′s diameter, and 400 times as far away. This coincidence means the Sun and Moon appear to be the same size when viewed from Earth.

During a total solar eclipse, in which the Moon is between the Earth and Sun, the Moon blocks the bright light from the Sun′s photosphere, allowing us to see the faint glow from the corona, the Sun′s outer atmosphere.

Why do the college professors and scientist say this was just a coincidence?

The orbit of the Moon around the Earth is elliptical in shape, with an average eccentricity of 0.0549, which is closer to a circle than most of the other planet orbits in our solar system.

Nevertheless, the orbit of the Moon is elliptical which varies in distance from the Earth. The closest point, called the perigee is 363,396 km from Earth, whereas the furthest point, called the apogee is 405,504 km away.

The orbit of the Moon around the Earth is at an inclination of 5.14° from the Earth′s orbital path, also know as the ecliptic plain. This slight variation keeps the moon out of sync with the direct line between the Earth and Sun for most of the moon′s orbit around the Earth.

Thus, an additional requirement for achieving a total eclipse (of either the Sun or the Moon) is for the Moon to be at one of the two locations in it′s orbit where the Moon crosses the Ecliptic plane, the locations which are call the lunar nodes.

The timing of the eclipse, type of eclipse and length of an eclipse depends entirely upon where the Moon is located relative to these two orbital nodes.

Lunar Orbital nodes are those two locations in the orbit of the moon around the Earth, where the Moon crosses the ecliptic plane. As previously mentioned, the ecliptic plane is that plane created by the orbit of the earth around the sun, which in the above diagram is shown in the two positions of its prograde orbit.

Orbital nodes for the orbit of the Moon around Earth are the two points where the Moon′s orbit intersects the ecliptical plane.

The node from which the Moon ascends northwards in the orbital plane is called the ascending node whereas the node from which the Moon descends southwards is called the descending node.

When the moon crosses through the area of an orbital node, a lunar eclipse can occur. In fact, the moon crosses the same node ever 27.21 days, a period which is called a Draconic month.

However, for an eclipse to occur, there are several other requirements necessary.

1. First, the Earth must be between the Sun and the Moon,

2. Second, the moon must be in the full moon phase, and

3. The Sun, Earth and Moon must be in or near syzygy.