Determining God’s Holy Days by Observation.

For anyone who is isolated and unable to get the published New Moon and Equinox times, which we currently use to determine the Holy Days, there is still a way of calculating the Holy Days with reasonable accuracy using nothing more than a stick, your hand and eyes.

This paper follows on from “A Basic Biblical Approach to Calculating God’s Holy Day Calendar”, and it may help to read that paper first. There is no doubt that a calculated calendar is more accurate, but those calculations are dependant on the published times for the equinoxes and new moons.

We know from Bible prophecy that things are going to get very rough before God and Christ come down to earth and install the Kingdom of God. We also know that war will continue right up to the time that the kings of the earth join together to fight our God and His Son at His return. In all this upheaval, we may well experience the loss of our current infrastructure, such as electricity and communications. What follows is written with this in mind. It is intended for emergency situations. Times when we are cut off from the normal way of knowing the New Moon and Equinox times, and therefore being able to use them to calculate the dates for the Holy Days. 

However, it also helps to demonstrate how dependant these calculations are on the relative positions of the sun, moon and earth (Gen 1:14).

Biblical Instructions.

The Bible doesn’t have a lot to say about how to calculate a calendar for keeping God’s Holy Days, however it does establish some important criteria that allows us to understand what is required.

Lev 23:10,11 implies that there should be some barley ready for harvesting during Unleavened Bread for the Wave Sheaf offering. Usually some barley is mature enough for a Wave Sheaf offering in the first week of April.

Ex 12:2 and Ex 13:4 identify the start of the year. Abib (H24) from Strongs means to be tender, or young ears of grain. We understand that this is another way of saying that the year starts in Spring (Northern Hemisphere {N.H.}).

From  Exo 23:16 NET.  "... , and the Feast of Ingathering at the end of the year when you have gathered in your harvest out of the field." 

and  Exo 34:22 NET.  "...  — and the Feast of Ingathering at the end of the year.",

we can learn that the Feast of Tabernacles is to be held after the Autumn equinox (“the year’s end”) and after the Summer harvest is gathered in.

For me, Ex 34:22 gives the clue that helps us to put the three points mentioned above, on a solid foundation. The phase “... at the year’s end.” (NKJV) or “... at the turn of the year.” (NIV), comes from the Hebrew word “tekufah” (Strong H8622,  "circuit, come about, end", which comes from H5362 "to knock together", or BDB "to strike"). There are two parts of knocking something together, you pull your arms back, then bring them together. In the same way there are two parts of a year - the sun heads North, and then crosses the equator and heads South.   As I understand it, Ex 23:16 and Ex 34:22 are saying that the Feast of Tabernacles must come after the Fall (N.H.) Equinox. In other words, when the days become shorter than the nights is the signal that the Feast may begin. When it actually begins is then a factor of when the New Moon began the month. From this verse, there is no restriction on Trumpets or Atonement being observed before the equinox - just that the Feast of Tabernacles starts after the equinox, in the Autumn.

Understanding the meaning of “tekufah”, and that the equinox that comes about three months after the shortest day (NH) is the start of Spring, then the Biblical new year cannot start until after that equinox has occurred. This is a key point - a major event (equinoxes, longest/shortest day) starts the next season Just as the first day of a month starts with a new moon in existence, so too the first month of the year has to start after the Spring equinox. Gen 1:14 indicates that the division between day and night is part of the “signs” we need to look at when considering the “seasons” or Festival times. As the two equinoxes (tekufahs) show us when the sun moves from one hemisphere to the other, and show us the change in the season, they are very fundamental to understanding God’s Holy Day calendar. The fact that pagans have taken on board something God made at creation and gave to His people, should not put us off from following God’s instructions.

Starting the year in Spring, after the equinox, eliminates any problem about starting the new year before the event (equinox) as you would have to do if you just took the New Moon closest to the equinox, since you cannot know (without charts) which of the two New Moons either side of the equinox are going to be closer, until at least two of the three events have occurred. Also, since many people want to start the year with the new moon closest to the equinox, I might point out that starting the year before the equinox will sometimes cause the Feast of Tabernacles to fall before the Autumn equinox, and this will go against the instructions in Ex 23:16, Ex 34:22. In simple terms, the year should not start before the 20th of March, and the Feast should not start before the 22nd of September.

With these factors in mind, what is required is a simple way of knowing when the Spring equinox (Northern Hemisphere) and new moons occur, and we can come up with a Holy Day calendar.

New Moons.

The easiest way I know of to estimate the new moon is to watch the old moon in the morning, just on sunrise. The moon moves about the width of your fist with your thumb stuck out and held at arms length, each day. Three or four days before the new moon, the moon is quite bright in the morning sky, and so it is easy to estimate how many hand widths from the moon to the just rising sun. I haven’t done it as yet, but I think it would be easy to make a triangle of wood and have a sighting nail pointed to a star close to the moon on the first day, and then add nails the same time each morning as the moon moves towards the sun. This would be a little more accurate than your hand. 

[I have since come across an article at that tells us how to do the calculations] 

However, using our hands can be very close, especially if you practice a bit by lining up the moon with the closest stars one night, and then check the next night at the same time, to see how far the moon has moved from the stars you selected the previous night. Having the right distance that the moon moves each 24 hours, work out the best hand position to just fit between the stars you selected the first night and the actual moon on the second night. Then estimate where the moon will be the next night - using the hand position you worked out - as a test for your estimation. Once you have a good way of judging the distance the moon moves across the sky in 24 hours, you are in a position to be able to estimate a few days in advance, when the sun is going to rise on the eastern horizon with the moon just behind it, which for our calculations will be the new moon. If it is too close to call, go to the following day. We want a new moon on the first full day of the month, not the last of the old moon. To put it another way, we want to know the first day that there is no moon in the sky at sunrise, so that we can declare the following day the first day of the month.


As I understand it, there are two ways of estimating the equinox, if you don’t have charts or a GPS. The first method is when the sun rises due East and sets due West. These directions can not be set with a compass (magnet North varies) but can be set from the stars. This will take time, but if you can note where the star at the North end of Orion’s belt rises, that will give you East, and where it sets will give you West. This works for both Hemispheres. Other, less well known stars, can be used as well. If you can identify either the North or South Celestial pole, then East and West are at right angles to a line running from earth and through a Celestial pole.

The second method of using the sun, is to find a spot where you can create a shadow from a straight stick both morning and evening. With a straight vertical stick at the center, put a marker on a circle - or draw a line on the ground - where the shadow falls each morning and evening. When the two markers and the center stick form a straight line, then the equinox has occurred. With this method, and by noting how much the shadow moves each day, you can estimate when the line will be straight, just in case the crucial day is cloudy. If all else fails, just remember that the Spring equinox in the Northern Hemisphere is usually on March 20th or 21st.

Measuring the time of daylight and darkness is not accurate, as it varies by days with latitude.  Of course, if you know your latitude and the number of days difference between equal light and dark and the equinox, then you could use it, but only in the Northern Hemisphere (it is after the event in the SH). However, this method becomes less accurate the closer you are to the equator, and the two previous methods become more accurate. The reason that daylight/darkness measurements are not accurate is because we do not use the center of the sun for measurements. Daylight starts with the leading edge of the sun, and ends with the trailing edge of the sun. Thus we have an error of the width of the sun.

The first new moon that occurs after the Spring (Northern Hemisphere) equinox, sets the start of the new year. Remember the month starts the day after the new moon occurs. To put it another way, the month starts the day that everyone around the world is under the New Moon. To keep the calculations consistent, we have taken the day as starting 6:00 pm (average sunset time) at the International Date Line.

Having determined the equinox and then the day after the first new moon after the equinox, we have established the start of the year. Then it is just a mater of counting out the days and months to God’s Holy Days. Each month is started with the same observations that we have outlined to start the year.

While it is possible to make mistakes using this system through, say, clouds stopping an observation, it is also self correcting. Each month can only have 29 or 30 days, so if you come to the 30th of a month without being sure of the next New Moon, you need to declare the next day as a beginning of a month regardless. By the same token, if you estimate the start of the next month after just 28 days, then you need to go to 29 days. Having a few longer (30 days)or shorter (29 days) months together will bring things back into line. Remember, even when using accurate conjunction times, there is no obvious pattern to the days in each succeeding month.

Applying Lev 23.

The New Covenant Last Supper is on the 14th day of the first month just after sunset, followed by the First Holy Day of Unleavened Bread on the 15th. The last Holy Day of Unleavened Bread is seven days later on the 21st of the first month.

Pentecost is 50 days after the Sunday that falls during Unleavened Bread (ULB), and is always on a Sunday. If the first Holy Day of ULB falls on a Sunday, count from that Sunday (Lev 23:15 “... day after the Sabbath ...”). We feel that the “day after the Sabbath” - the Sunday - is the one required to fall during Unleavened Bread, as it is the one we are told to count from.

Trumpets falls on the first day of the seventh month. This is the one Festival that has the potential to catch us unawares. However, we know from the start of the sixth month, that Trumpets will come either after the 29th or 30th day. Weather permitting, you can usually get an idea of when the New Moon will happen two or three days in advance, so we should have a few days notice. Atonement is ten days after Trumpets, and the Feast of Tabernacles starts on the 15th of the seventh month. The Last Great Day and is on the 22nd of the seventh month.

Length of the Year.

Just like each month having 29 or 30 days, each year will have 12 or 13 months. If we are using only observations to set our calendar, then there is no easy way to predict in advance what each year is going to be. If we get to the end of the 12th month and the equinox has not occurred, then obviously we need a thirteenth month that particular year.

While having a calendar calculated from published New Moon and Equinox times is preferred, the fact that we can keep a calendar by just observation shows how “tied in” we are to “signs [that] indicate seasons and days and years” Gen 1:14 (NET)

One final point.

1 Ch 28:9 (NLT) “And Solomon, my son, get to know the God of your ancestors. Worship and serve him with your whole heart and with a willing mind. For the LORD sees every heart and understands and knows every plan and thought. If you seek him, you will find him. But if you forsake him, he will reject you forever.”

If we stop and think about these words of David spoken to his son Solomon, we can see that our attitude and motivations are well known to God. Therefore, we should keep the Holy Days in honour of God’s commands, and with deep gratitude for His marvelous plan that they outline. It is my hope that just because different groups use different methods of calculating the Holy Days, we will still be willing to encourage those who “keep the Feast” on whatever day they choose. In time Christ will make it clear what method we are to use to calculate the Calendar, and we have to allow that it might not happen till He returns to earth and helps set up the Kingdom of God. Until it is confirmed by God, we can only do what we feel is right, and encourage others to do the same.

Bob Orchard 

While this information is made freely available (Mat 10:8b) , and can be printed out, it is done with the understanding that there will only be fair and honest use of the material, and that it will be copied in full with no alterations.

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