The Broad and Full Passover Moon—31 A.D.

Moon over Gethsemane

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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 the historical reckoning of Daniel's 70 weeks. The Bible pins the seventy-week prophecy to the beginning of the 2300-day prophecy. Ellen G. White has said clearly that the 2300 days (years) ended on October 22, 1844. Therefore, the entire Adventist theology stands or falls on the validity of the 31 AD crucifixion date.

Critics have suggested that there could not possibly have been a full moon on the eve preceding the crucifixion in 31 AD. Some have even lost faith that God has fulfilled Daniel's 2300-day prophecy. Some facts of interest should be considered, however, before one abandons the venerated interpretation of Daniel's prophecy.

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

Passover was a seasonal event that occurred during springtime. The actual date of Passover, like all the seasonal festivals, fell out as soon after the vernal equinox as possible according to the correct phase the moon. 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 from consideration because it would have occurred too early in the season, and its occurrence was inconsistent with the evident days of Passion Week. The lunation that began on May 12 would have begun too late in the season for consideration. Therefore, this study examines the lunation that began on April 10, 31 AD at 14:25 TDT (1:34 PM local Jerusalem time).

new versus full moon image

We cannot precisely say, as yet, how the Hebrew calendar functioned during the first-century when Christ walked among us. People of the diaspora developed the modern Hillel II calendar during the fourth century AD. The calendar does not base its structure 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 they managed their calendar during Bible times based on scriptural evidence, the Elephantine papyri, and known calendric systems that were used by surrounding nations. Since the people who lived in the ancient Levant based their lunisolar calendar on the motions of the sun, moon, and earth, we should first review some astronomical basics.

new moon conjunction

Conjunction and Opposition

When a single, geometric plane bisects the moon, sun, and Earth, we say the three bodies are in conjunction. The astronomical new moon occurs at conjunction when the moon is between the sun and Earth. During this time, 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." Astronomical full moon, the point of greatest reflection occurs when the moon revolves 180-degrees to opposition on the opposite side of the earth. As the moon continues its revolution and returns to new-moon conjunction again, the cycle is complete. The moon has rendered each of its phases. We call a full revolution of the moon a lunation, and it currently lasts about 29.530588 days. While the moon advances from new moon to full moon, we say it is waxing, and as it moves from full moon to dark moon, we say it is waning.

The Inconstant Moon

Anomalies and Perturbations in the moon's orbit.

Momentum and a gravitational attraction to other celestial bodies both govern the path of an orbiting sphere like the moon. Gravitational attraction between each body is proportional to their mass and the distance between them. The low mass of the moon allows it to be easily tugged and pulled by the earth, sun, and large planets. Any deviation of a celestial body from its orbital path caused by a gravitational pull from other celestial bodies is known as a perturbation.

The circuit of any orbiting body is elliptical and not circular. Major bodies, like planets, have a low eccentricity, so their orbits are nearly circular. Unlike a circle which has one focus point, the center, an ellipse has two, uncentered foci that lie along the major axis. Since the larger, orbited body holds a position 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. These factors produce anomalies of motion. The moon has a comparatively high eccentricity and, therefore, high anomalies of motion. The time it takes for the moon to complete an elliptical orbit is called an anomalistic month and is about 27.55455 days.

Despite all of these perturbations and anomalies that affect the moon's orbit, it really achieves a splendid harmony with the motions of Earth while the whole earth-moon system revolves around the sun. 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

From early times, the Hebrews and other surrounding nations used a lunisolar calendar system. Such a system establishes months according to the phases of the moon and adds additional months to the year occasionally to keep in step with the solar year. In early times, the beginning of a month commenced with the first sighting of the new moon. Some nations, like Babylon and Persia, began to use an artificial calendar based on the 19-year Meton cycle. That recurring cycle loosely harmonized the phases of the moon with the tropical year. Even though artificial, the design of those artificial systems still attempted to place the beginning of the month so that it coincided as closely as possible with the first sighting of the new moon.

As the old moon wanes, its visibility diminishes until it 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. If the moon was first observable to the human eye on the 29th day of the month, that month officially ended, and the governing officials declared a new month. If the moon was not visible on the 29th day, the current month continued for one more day and became a thirty-day month. Since the synodic month is slightly longer than twenty-nine and one-half days, thirty-day months occur a bit more often than twenty-nine-day months.

The crescent sliver could be visible in as few as eighteen hours after conjunction but may not be visible until the third day after conjunction. So the full moon conjunction usually occurs on the 13th or 14th day of the Jewish month. The Passover moon of the 14th and 15th, although already beginning to wane, 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 Gethsemane event. Ellen White wrote that 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 move into conjunction and immediately pass out of it 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 that night. The moon typifies 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 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

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 quickly. We can loosely graph the rate of lunar phase change as a sine wave. As illustrated above, we can see that for a given time period, the rate of phase change varies markedly. 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 the opposition, the moon was still full. In fact, the illuminated fraction would have only changed by one degree which is indiscernible to the naked eye.

Passover moon

A moon that is close to the horizon gives the illusion of being massive. Its size may be the same as when it is more overhead, but its appearance, contrasted with fixtures along the landscape, is impressive. The Passover 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. A new moon rises at sunrise and sets at sunset. Since a day had elapsed since the opposition, the moon would have risen later than sunset and would have had to clear the Mount of Olives before it was visible to the garden in the valley.

The disciples arrived at the upper-room before the sun had set. After the group finished eating, the Bible says that Judas left the room, and "it was night." Jesus continued teaching the others for some time. They sang hymns and psalms that were customary of 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 the pilgrims attending the festival who were "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 calculations that the moon was ninety-nine percent illuminated just before midnight and remained greater than ninety-eight percent illuminated the rest of the night. This amount of illumination is indistinguishable from a moon that is 100 percent illuminated at the opposition.

Perigee and 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. This action 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 where it changes direction again towards perigee, and the cycle continues.

As we know, objects that are nearer appear larger than objects farther away. So the apparent 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 on or near perigee, it is called a super moon. The moon has a synodic period of 29.53059 days and an anomalistic period of 27.55455 days. The beat time of these two periods is 411.78 days. Loosely speaking, there are fifteen anomalistic months per fourteen synodic periods. The harmony is not perfect, however, so the coincidence may slip out of phase every so often. Seldom does the full-moon opposition occur precisely during perigee. Therefore, the term super is relative. The disk size of the moon changes significantly from apogee to perigee. The closer to the full moon, the more super is 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 opposition, 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 placed an active verb, shone, in this passage that gave the moon a participating role in the events that transpired that night. The moon 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. His sin separated man from God and mankind began 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 righteous woman mentioned in 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


The moon shines the brightest on a cloudless night. The atmosphere diminishes the light we receive from the moon even with the absence of clouds. So the best light shines when the moon is overhead as opposed to being close to the horizon because the light rays take a more direct path through the atmosphere. That night, the moon would have necessarily been high enough in the sky to clear the Mount of Olives as viewed from the Kidron Valley.


The most obvious factor that affects the brightness of the moon, associated with its phase, is the area of the disk that sunlight illuminates. A full moon is much brighter than a quarter moon, and a new moon casts no light at all. But the area of illumination is not the only factor that affects brightness. Another phenomenon that we call opposition effect progressively intensifies the brightness of the moon as its phase changes from new to full. Otherwise stated, the brightness changes increasingly as the moon's elongation decreases from 180 degrees to zero degrees. Some use the term, phase angle interchangeably with elongation, although phase angle usually refers to an orbiting body's elongation as 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 zero. When the elongation is 180 degrees, there is no opposition. The full moon opposition has the lowest elongation. The elongation during a full moon is seldom actually zero degrees because the moon's orbit is not in the same geometric plane as the ecliptic. Likewise, the elongation during a new moon is seldom 180 degrees. When the elongation is either zero or 180 degrees, an eclipse occurs.

Several factors combine to produce opposition-effect. The most significant factor involves the way that sunlight casts shadows on a surface. For example, when we look at our shadow while the sun is directly above, we may only see the outline of our head. The sun's position tucks the rest of our shadow underneath our feet. As we look around, other objects similarly have little or no shadow because 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. We call this phenomenon, opposition surge. We cannot observe this phenomenon at elongations under one degree because the sun eclipses the moon at such low elongation. An average elongation at full moon opposition is about three or four degrees or so.


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

The distance between the moon and the earth is a major factor that determines its brightness. Light intensity decreases inversely with the square of the distance involved, and as we noted, the distance of an orbiting body changes continually from apsis to apsis. During the first century, Passover always occurred when the earth was near aphelion which means the earth-moon system was at the farthest extreme from the sun. The anomaly does not affect the intensity of sunlight that falls on the moon much because of the low, orbital eccentricity traveled by the earth-moon system. The small orbital changes in distance compared to the very large distance involved produces an 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 small by comparison. Therefore, moonlight intensity changes more dramatically as the moon circuits the apsides.

In summary, the full moon that occurred during Passion Week would have been brighter than usual due to the moon's very low phase angle and its proximity to perigee. During the next day, while the disciples were preparing the Passover, the phase angle would have continued to grow, and moonlight intensity caused by opposition effect would have been lowering. At the same time, however, the moonlight's radiance was intensifying 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. Even from some distance away, the keen-eyed disciple, John would have seen that Jesus was in agony and that "...his sweat was as it were great drops of blood falling down to the ground."


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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