Moon Over Gethsemane

EGW Quote
In company with His disciples, the Savior slowly made His way to the garden of Gethsemane. The Passover moon, broad and full, shone from a cloudless sky. The city of pilgrims' tents was hushed into silence. DA p:685

Adventists hold that Christ died during the Passover of 31 AD according to historical reckoning of Daniel's 70 weeks. Since the 70 weeks are pinned to the beginning of the 2300 day prophecy, and EG White has unambiguously stated that the termination of the 2300 days was October 22, 1844, the entire Adventist theology stands or falls with the validity of the 31 AD crucifixion date.

Critics have suggested that there could not possibly have been a full moon on the eve of the crucifixion in 31 AD. Some have abandoned their faith that Daniel's 2300 day prophecy has been fulfilled. There are some facts of interest that should be considered before abandoning the venerated interpretations of Daniel's prophecies.

bible verse one
He appointed the moon for seasons: the sun knoweth his going down. Psalms 104:19

Passover is a seasonal event that occurs during springtime. The actual date of Passover, like all the seasonal festivals, is determined by the way the sun reflects the movements of the moon according to scriptural directive. There are three possible lunations in 31 AD during which the Passover could have occurred: The first possible lunation began with the new moon of March 12, the second began with the new moon of April 10 and the third possibility began with the new moon of May 10. The March 12 lunation can be dismissed as being too early and not conforming with evident days of the passion week. The lunation that began May 12 can be considered to have begun too late in the season. This study examines the lunation that began on April 10, 31 AD at 14:25 TDT (1:34 PM local Jerusalem time).

We can not say with completeness as yet how the Hebrew calendar functioned in the first century during the second temple period. The modern Hillel II calendar was developed in the fourth century A.D. That calendar is not based on lunar observance but makes use of the 19-year meton cycle with variations to accommodate Sabbaths and holy days. We do, however, possess a well developed model of how calendration was accomplished during Christ's first advent based on scriptural evidence, the elephantine papyri, and known calendars used by surrounding nations of antiquity. Since the luni-solar calendar of the ancient Levant was based on the motions of the sun, moon and earth, we should first review some basics.

new versus full moon imagenew moon conjunction

When the moon, sun and Earth are bisected by the same geometric plane, they are said to be in conjunction. The astronomical new moon occurs at conjunction when the moon is between the sun and Earth. The moon does not appear to reflect sunlight because we see the side that is facing away from the sun. We sometimes refer to this condition as the "dark of the moon." When the moon orbits around to the instance of conjunction on the opposite side of the Earth, astronomical full moon and maximum reflection is achieved. As the moon revolves halfway around the earth again and reaches the instance of conjunction to astronomical new moon, the cycle is complete. Each phase of the moon has been rendered. This is called a lunation and lasts about 29.53058 days. While the moon advances from new moon to full moon, it is said to be waxing, and as it moves from full moon to dark moon, it is said to be waning.

The Inconstant Moon

The path of a celestial body is determined by the angular momentum it possesses and the gravitational attraction of other neighboring bodies. Gravitational attraction is related to the mass of each body and the distance between them. An orb's circuit is elliptical and not circular although the eccentricity of major bodies, like planets, have a fairly low eccentricity. The moon, however, has a comparatively high eccentricity. The low mass of the moon allows it to be easily tugged and pulled by the earth, sun and large planets. These factors result in anomalies and perturbations in the moon's orbit. The motions of an elliptical orbit itself is an anomaly. In fact, the time it takes for the moon to complete an elliptical orbit is called an anomalistic month and is about 27.55455 days. Unlike a circle which has one focus point, the center, an ellipse has two foci which are not centered along the major axis. Since the body being orbited is positioned at one of the focal points, the distance of the orb from the orbited body varies throughout the cycle. Kepler has shown us that the speed varies as well. Despite all of these anomalies, a splendid harmony is achieved. The moon, at any given hour, is exactly in the place God appointed.

bible verse one

The sun also arises, and the sun goes down, and hastens to its place where it arose. The wind goes toward the south, and turns about unto the north; it whirls about continually, and the wind returns again according to its circuit. All the rivers run into the sea; yet the sea is not full; to the place from where the rivers come, thither they return again. Ecclesiastes 1:5-8

To every thing there is a season, and a time to every purpose under the heaven. Ecclesiastes 3:1

First Visible Crescent

As the moon wanes, it becomes a thin sliver crescent and finally disappears from view a day or more before new moon conjunction. After two or three days, the moon reappears as a thin, waxing crescent setting on the western horizon just after sunset. When the moon is first observable to the human eye on the 29th day of the current month, a new month is declared. If the moon is not visible, the current month continues for one more day and will be a month of 30 days as opposed to a 29-day month. If the moon is visible just after sunset on the 29th day, the first visible crescent is established and the new month is declared.

The crescent is first visible in as little as 18 hours after conjunction, but may not be visible until the third day after conjunction. The month might not begin until well after new moon conjunction so the following full moon usually occurs on the 13th or 14th day of the Jewish month. The Passover moon is usually already technically waning yet is still very much a full moon in appearance.

The April astronomical full moon under consideration occurred on Wednesday, April 25, 31 AD at 10:55 PM GMT. This would have been near a full day prior to the agony of Gethsemane. Ellen White said the moon was shining "broad and full" when the Savior entered the garden with His disciples. Is she in error?

Defining Terms

Full moon conjunction is an instantaneous event. The bodies involved move into conjunction and immediately passes out of conjunction again. The moon may appear full, however, over several evenings when it is near conjunction. When we step outside and see the moon on nights like these, we can rightly say, "there is a full moon tonight." Ellen White was writing prose when she penned this chapter and portrayed a scene that is integral to the story. She accurately used the phrase "broad and full" to paint the landscape that was the backdrop to the Lord's anguish and suffering. The moon typified the law, the Old Testament and all the prophets. As He walked along, the clear visibility of that great timepiece would have been a constant reminder that the fullness of time had come and that the consummation of all the Old Testament types and sacrifices would now rapidly fall upon Himself. A piece depicting the night of Gethsemane without mentioning the Passover moon, would be incomplete. Now we can look back and consider whether the moon would have appeared to shine broad and full upon the olive garden that fateful night.

Full and Broad Moon

sinusoidal change Passover moon

The rate of change in moon phase is not constant. New moons and full moons seem to linger whereas quarter, crescent and gibbous moons change phase quite quickly. If the orbit of the moon was circular and its velocity remained constant, we could graph the rate of change as a sine wave. The actual graph would be somewhat distorted based on eccentricity. As illustrated here, we can see that for a given time period, the change in moon phase can be quite different. The most rapid change in phase occurs at quarter moons, and the least change occurs during new and full moons. Although Christ and His disciples entered the garden a full day after conjunction, The moon was still full. In fact, the illuminated fraction would have only changed by one degree which is indiscernible to the naked eye.

A moon close to the horizon gives the illusion of being massive. The size may be the same as when it moves higher in the sky, but the appearance when contrasted with fixtures along the landscape is impressive. The moon would have risen over the Mount of Olives to the east of Jerusalem. A full moon rises at sunset and sets at sunrise. As it wanes from full to new moon, it rises progressively later each night The new moon rises at sunrise and sets at sunset. Since a day had lapsed since conjunction, the moon would have risen later than sunset and would have had to clear the Mount of Olives before it became visible to the garden in the valley.

The disciples arrived at the upper room before sunset. After the meal, the Bible says Judas left the room and it was night. Jesus continued to instruct the others for some time. They sang hymns and psalms customary to the Pascha. The path to Gethsemane would have led the group down Old Mount Zion to the Kidron Valley where the garden and olive presses were located. They passed along the booths and tents of pilgrims "hushed" in silence. Therefore, it must have been a late hour - say 10:00 PM. Even so, from their position in the valley, the moon may not have been far above the crest of Olivet and therefore displayed the illusion of great size. We will not know for certain until and unless those scenes are replayed again someday.

We do, however, have ephemeral data that can help us determine whether the moon was full and broad that night. We know from calculation that the moon was 99% illuminated just before midnight and remained greater than 98% illuminated the rest of the night. This amount of illumination is indistinguishable from a moon 100% illuminated at conjunction, but there is more.

Perigee and Apogee

perigee-apogee

As mentioned, the moon orbits the Earth along a fairly eccentric elliptical path. The Earth occupies the space of one of the two foci associated with that ellipse. Since the foci are not centered and an ellipse is not a circle, the distance of the moon from Earth is constantly changing. The point where the moon is nearest to Earth is called perigee, and the farthest point is called apogee. The gravitational pull exerted on the moon as it nears perigee accelerates its velocity which sling-shots the moon around, beyond and away from the Earth towards apogee. The Earth's gravitational attraction now acts against the moon's velocity and momentum until it reaches apogee and changes direction again towards perigee as the cycle continues.

Obviously, objects that are nearer appear larger than objects farther away. So the size of the moon's disk grows considerably larger as it nears perigee and becomes smaller when approaching apogee. When a full moon phase occurs while the moon is at or near perigee, it is called a super moon. Full moons occur every synodic period of 29.53059 days, and the moon returns to perigee every anomalistic period of 27.55455 days. The beat time of these two periods is 411.78 days. Loosely speaking, there are 15 anomalystic months per 14 synodic periods. The harmony is not perfect, however, so the coincidence may slip out of phase every so often.

Seldom does a full moon conjunction actually occur within an hour of an incidence of perigee. Therefore, the term super is relative. The larger concept to be understood is that the disk size of the moon changes significantly from apogee to perigee. The closer the full moon, the more super the full moon. Full moons that occur nearer to apogee are termed micro moons.

On the Sunday preceding Passion Week, April 15, 31 AD, the moon was at apogee. Twelve days later, on April 27, when Christ was on the cross, the moon achieved perigee. Full moon conjunction, Wednesday, April 25, occurred less than two days prior to perigee, so the disk was comparatively large and growing as the moon continued its travel closer to Earth. The struggle at Gethsemane would have taken place just hours before perigee. The still full moon would have been broad indeed.

Shone from a Cloudless Sky

The passage mentions that, "The Passover moon, broad and full, shone from a cloudless sky." Mrs. White chose a non-passive verb, shone, in this passage giving the moon a participating role in the events that transpired that night. It was not just nestled in the background but had action. It was shining.

The moon has virtually no luminescence of its own. It simply reflects the light apportioned to it from a true and greater source of light. Yet, it is the lesser light which rules the night. Four thousand years of night had passed since the fall of Adam. Man was separated from God and living in darkness - but not total darkness. Through the law, the prophets and the sacrificial system, God revealed Himself to His people. In kind, those people were to reflect the light given them to others. Sadly, this seldom happened. Nevertheless, the lesser light had accomplished its mission, the woman of Revelation, clothed with the sun, was now standing on the moon. Because of Gethsemane and the cross, Christianity would shine on the world like the sun.

Factors Affecting Brightness

moon-earth-sun

The moon shines the brightest on a cloudless night. Light from the moon is diminished as it passes through the atmosphere even with the absence of clouds. So the best light shines when the moon is overhead as opposed to being close to the horizon. This is because the light passes through less of the atmosphere surrounding the Earth. To be seen, the moon would have been high enough in the sky to clear the Mount of Olives as viewed from the Kidron Valley.

moon-brightness-graph

The most obvious factor affecting the brightness of the moon is the area of the disk that is illuminated and is associated with its phase. A full moon is much brighter than a quarter moon, and a new moon casts no light at all. But there is more involved than just the area of illumination. A phenomenon called opposition effect progressively intensifies the brightness of the moon as the phase changes from new to full. Otherwise stated, the brightness changes increasingly as the moon's elongation decreases from 180 degrees to 0 degrees. Elongation is often used interchangeable with phase angle, although phase angle usually refers to the elongation projected onto the ecliptic plane.

elongation illustration

The elongation is the angle of reflection from a light source shining upon an object in front of you. If the light source is directly behind you and the reflecting object is directly in front, the source and object are in opposition and the elongation is 0. When the elongation is 180 degrees, there is no opposition. The full moon conjunction has the lowest elongation. The elongation at full moon is seldom actually 0 degrees because the moon's orbit is not in the same geometric plane as the ecliptic. Likewise, the elongation at new moon is seldom 180 degrees. When the elongation is either 0 or 180 degrees, an eclipse occurs.

Several factors contribute to opposition effect. The most significant is related to shadow casting. When the sun, for example, is directly overhead, and we look down at our shadow, we may only see our head. The rest of our shadow is tucked underneath our feet. As we look around, other objects similarly have little or no shadow. The sun is in opposition. When the sun is low in the sky, however, there is little opposition and we cast a very long shadow. The moon has a rough and granular surface creating a matrix of shadows when the elongation is large, but those shadows dissipate at opposition. The change in brightness as the elongation lowers is not linear. At very low elongations, say under a few degrees, the brilliance becomes significant producing somewhat of a light flash. This phenomenon is called opposition surge. This effect cannot be observed at elongations under 1 degree because the moon would be eclipsed. An average elongation at full moon conjunction is about 3 or 4 degrees or so.

april-25-31-eclipse

The elongation during full moon conjunction on the Wednesday evening preceding the crucifixion was a very low 0.84 degrees. In fact, a partial lunar eclipse occurred that night a few hours after sunset and would have been viewable to an observant onlooker in the area. Just prior to and after that event, the moon would have been quite bright.

A major factor determining the brightness of the moon is the distance between the bodies involved. Light intensity decreases inversely with the square of the distance, and as we noted, the distance of an orbiting body changes continually from apsis to apsis. Back in the first century, Passover occurred fairly near aphelion which means the Earth-moon system is at the farthest extreme from the sun. This does not have much effect on the average light intensity reaching the moon though because of the low eccentricity of the Earth-moon system orbit. The small orbital changes in distance compared to the very large distance of the system from the sun produces a somewhat insignificant difference in light intensity from aphelion to perihelion.

In contrast, the moon's orbit around the Earth is much more eccentric, and the overall distance between the two bodies is very small in comparison. Therefore, light intensity reflected to Earth changes much more dramatically as the moon circuits the apsides.

In summary, the full moon conjunction of passion week would have been brighter than usual due to a very low elongation and the moon's proximity to perigee. During the next day, while the disciples were preparing the Passover, the moon's elongation would have been growing thereby reducing the radiance caused by opposition effect. That reduction, however, was being offset in some measure by radiance added as the moon continued to approach perigee. Late Thursday night, as the group descended Zion toward Gethsemane, the elongation would have still been a fairly low 13 degrees, and the moon's proximity to perigee would have been less than 16 hours. On a clear night, the moon would have been brighter than average. Though some distance away, the three disciples would have seen Jesus was in agony and that "He prayed more earnestly, and his sweat was as it were great drops of blood falling down to the ground."

Conclusion

Through our study, we have found no factual doubt regarding the following passage from "The Desire of Ages" written by Ellen G. White:

EGW Quote
In company with His disciples, the Savior slowly made His way to the garden of Gethsemane. The Passover moon, broad and full, shone from a cloudless sky. The city of pilgrims' tents was hushed into silence. DA p:685

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