Happy Eclipse Year

After a long wait, the Eclipse Year is finally here!  I've been waiting for the 2024 total solar eclipse over Cleveland since first hearing of it on the day of the annular eclipse over Cleveland, May 10, 1994.  I was 33 at the time and reckoned that I'd be 62 years old on the day of the eclipse in 2024.  That seemed incomprehensibly far off in the distant future for a young guy in his early 30s.  And yet suddenly, abruptly, here I am, nearly double my age, with only three months remaining until the long-awaited date.

Scripture includes lessons on the brevity of life, such as these:

Whereas ye know not what shall be on the morrow. For what is your life? It is even a vapour, that appeareth for a little time, and then vanisheth away.  -- James 4:14
 

The days of our years are threescore years and ten; and if by reason of strength they be fourscore years, yet is their strength labour and sorrow; for it is soon cut off, and we fly away. -- Psalm 90:10

These verses bounced off me as a young person who had not yet lived long on the Earth.  I indulged in the vanity that I still had lots of time.  Yet the truth of the Scriptures hits you upside the head when you actually see your own life vanish away like a vapor, and you rapidly approach "threescore years and ten."  On a practical level, eclipse cycles are a hard teacher in the lessons of the fleeting nature of a human lifetime. 

Eclipses operate over long cycles, some decades in length and others over the span of centuries.  You can look ahead and see eclipses beyond your own allotment of years.  There will be total solar eclipses over the USA in 2044 and 2045 that might span my lifetime, maybe even 2052 if I make it be a really old geezer.  But the eclipses of 2071, 2078, 2079 and 2099 only await my grandsons, now toddlers.   

It's incredible that eclipses can be calculated with such precision centuries in advance.  It is truly a type of "Scientific Calvinsim" that eclipses are predestined to occur.  The solar system bodies move in perfectly predictable celestial clockwork, on the smooth, frictionless bearings of their orbits, tugged along by their mutual gravities.  

It is also amazing that these motions proceed along mathematical principles that can be comprehended by the human mind, which have been extracted over the last several centuries of modern scientific methodology.  The LORD hid these principles in plain sight, but equipped His human creatures to study and investigate and understand.

It is the glory of God to conceal a thing: but the honour of kings is to search out a matter. -- Proverbs 25:2

Among the principles uncovered by modern science is that the Moon (and other solar system bodies) moves in regular motions according to orbital elements.  These are properties of the Moon's orbit that orient the Moon's motion according to the coordinate system of the sky as viewed from Earth.  A brief discussion of orbital elements was included in this recent newsletter from last October. 

That previous newsletter mainly discussed the eccentricity of the Moon's orbit that can produce total solar eclipses or annular eclipses.  This newsletter will explain a bit more about the inclination of the Moon's orbit (i in the image above), how the plane of the Moon's monthly motion is slightly tilted to the plane of the Earth's orbit.

Another orbital element is Ω, a capital Greek letter omega, signifying the ascending node of the Moon's orbit.  The nodes are the points where the Moon's inclined orbit crosses the plane of the Earth's orbit (AKA the plane of the ecliptic, as understood by readers of Signs & Seasons,

As a result, the shadow of the Moon falls upon the Earth, causing a solar eclipse, and the Moon passes through the Earth's shadow, resulting in a lunar eclipse.  And during a solar eclipse, at least a portion of the Sun is obscured as seen from somewhere on the Earth.

As also mentioned in the recent newsletter from last October, the nodes remain aligned in the same straight-line general direction even as the Earth moves in its circular orbit around the Sun.  So eclipses occur in eclipse seasons in months when the nodes are aligned.  Eclipse seasons occur in opposite seasons of the year, when the Earth is on opposite sides of the Sun.  In these opposite seasons, the nodes align with the Sun, so that eclipse can occcur.  Eclipses cannot occur in the months between eclipse seasons, when the node are not aligned with the Sun.    

In such months between eclipse seasons, the Moon does not cross over the Sun, but passes to the north or south of the plane of the ecliptic at the New Moon.  There can be no eclipse since the Moon's shadow does not fall upon the Earth.  No portion of the Sun is obscured by Moon, as viewed from anywhere on Earth.  (For more detailed information, check out the Eclipses Explained page and video at our eclipse site.)

They are called "eclipse seasons" because more than one eclipse occurs per season.  Eclipses always come in pairs, and there is always a lunar eclipse to accompany a solar eclipse in the same lunation (i.e., lunar month).  Sometimes the lunar eclipse comes first and then the solar eclipse comes after, two weeks later.  This is the shortest eclipse cycle, called a fortnight.  In other seasons the solar eclipse comes first and then the lunar eclipse occurs a fortnight later.   Some eclipse seasons include three eclipses, where two solar or lunar eclipses sandwich one of the other in between.