the sea and the waves roaring. - Luke 21:25 

 

 

 

 

 

 

 

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Moonfinder Storybook!
We have received some very favorable feedback about our illustrated family storybook, Moonfinder.  As mentioned in the last newsletter, Moonfinder is the story of a little boy who learns about the phases of the moon with his dad.  Moonfinder  is a full-color 32-page picture book, for small kids and for other readers of all ages.    

 

 

 

 

I just read a copy of Moonfinder. The illustrations are beautiful and the information was great. I love the idea of moonfinding with the kids and then being able to explain why the moon is in different places during the month. I wish I could have read this book when I was kid, cause I never really understood why the moon moved the way it did. - Stacey from Bright Ideas Press

 

 

Please check out the Moonfinder page at our website.  If you don't have small kids of your own, Moonfinder would make an excellent gift for a niece or nephew, a grandchild, or any other child in your life!  Moonfinder would also be a great introduction to observing the sky for students not yet ready for our Signs & Seasons curriculum!

 

Friends, if you like receiving the Update and the information we provide, please prayerfully consider ordering a copy of Moonfinder.  Sales of the products from our store help us pay for our costs in maintaining the site and providing this newsletter.  To tell you truth, we've only sold a handful of copies of Moonfinder in the first month, which is not exactly encouraging after so great an investment of time, effort and famiy funds. 

 

Our family has created Moonfinder and Signs & Seasons to help families like yours learn about the beautiful and remarkable clockwork that the LORD has established in the sky above!  Many thanks to everyone who has supported our efforts!    

 

Moonfinder and Signs & Seasons will be available at homeschool conventions through Grace & Truth Books.  Stop by their booth at your homeschool convention! 

 

 

The Astronomy of Easter
Since the early centuries of the church, Christians have honored the death and resurrection of Jesus in the celebration of Easter. And while the observance of Easter has changed over the centuries, it is based on the Hebrew Passover.

 

The Paschal Moon
The Paschal Moon is the first Full Moon after the Vernal Equinox, and signals the arrival of Easter the next Sunday.Is Easter Pagan? ("Pagan Influences?" Series)
The feast of LORD's resurrection, commonly known by the name Easter in the English language, is one of the most ancient observances in Christianity. However, in recent years, there has been an increasing trend among evangelicals to shun Easter as allegedly being derived from a pagan source. This article examines some of the "urban legends" surrounding this claim.

 

According to the reports, an astrologer (not an astronomer) was predicting that the Moon's gravity would cause massive earthquakes as the pull from the Moon would disrupt the Earth's crust.  A similar report came from a gentlemen who claimed to have predicted the 1989 World Series earthquake.  In the wake of the tsunami that had just devastated Japan, many people were fearful that the worst was yet to come. 

 

After a few days, reassuring reports were released by NASA and professional scientists, debunking the alarmists.  As we all saw, the Supermoon last Saturday came and went with no further devastation.  However, the mainstream media failed to explain exactly why there was no cause for concern, since one rarely receives an adequate science lesson through the press.  In this article, we'll examine the nature of the Moon's orbit and explain why there is no risk from the normal motion of the Moon around the Earth.

 

 

Anyone who lives near the ocean understands that there are tides each day, when the level of sea of changes.  The rest of us who live inland only hear about the tides!  The high tide is when the water level is maximum and low tide is when the level is miminum. 

 

There are two tides each day, and they are associated with the Moon.  There is a high tide when the Moon is somewhat past the meridian, and another high tide on the other side of the day, when the Moon is below the horizon, having invisibly passed the lower meridian.  (The meridian and also the Moon's monthly cycle are explained in detail in our Signs & Seasons curriculum.) 

 

 

 

 

 

 

 

There are many factors that affect the time and the level of high tide.  Some have to do with geography.  The shape of a coastline can cause the water to pool up, increasing the level of high tide at a particular location.  A different shaped coastline can cause the opposite effect.  The coastline creates "drag" on the water, causing the tide to roll in sometime after the Moon's meridian passage.  The tide rolls from east to west due to the Earth's rotation, so that the tide slams into the east coast of the USA, which therefore results in a higher tide than oberseved on the west coast. 

 

Of the two tides each day, one high tide is always higher than the other.  Basically, this varies with the seasons, having to do with the Moon's position in the constellations of the zodiac.  When the Moon is in Gemini, it passes higher overhead in the latitudes of the northern hemisphere, so that the tide levels to the north are higher.  Similarly, when the Moon is Sagittarius, the Moon is high above the latitudes of the southern hemisphere, but low in the skies to the north, so that high tide in the northern latitudes is lower.

 

In addition to the Moon, the Sun also helps raise the tide.  The Sun is massive compared to the Earth, and its gravity keeps the Earth in its orbit.  However, the Sun is also 93 million miles away.  Nonetheless, the Sun's gravity for raising the tide is a bit less than half the strength of the Moon, so that the Sun contributes about 1/3 of the total tide. 

 

When the Moon and the Sun line up at New Moon and Full Moon, the gravities of these two bodies combine to pull the tide in the same general direction.  These are the highest tides, known as spring tides.  The weakest tides occur when the Moon and Sun are perpendicular, so that their gravities cross and do not add together.  These are the neap tides. 

 

 

 

The Moon's orbit is not perfectly circular.  It was shown by Johannes Kepler in his work New Astronomy, published in 1609, that the orbit of the Moon and also the orbits of the Earth and the other planets are actually in the shape of an ellipse.  Because of this shape, the Moon orbits the Earth in an off-center fashion.  This is the eccentricity of the Moon's orbit. 

 

There is a time each month when the Moon is closest to the Earth, and another time when the Moon is farthest away from the Earth.  The Moon is closest to the Earth at perigee, and farthest from the Earth at apogee.  These words come from the Greek root word ge which means Earth (as in "geography") and also the Greek words peri and ap, which can respectively be construed to mean near and far. 

 

 

When the Moon is at perigee, it is closest to the Earth, and the lunar component of the tide is therefore the strongest.  Conversely, when the Moon is apogee, it is farthest from the Earth, and therefore the Moon's influence on the tide is weakest.  For this reason, perigean spring tides are the highest tides of all, since the Moon's pull on the oceans is strongest, and since the Moon's gravity tugs in the same direction as the Sun.  Similarly, apogean neap tides are the weakest, because the Moon is farthest away from the Earth, thus pulling in a cross direction to the Sun.    

 

The tricky part comes into play because the Moon's perigee and apogee are constantly shifting around.  In any given month, the Moon can be in any phase when it reaches its closest and farthest distances from the Earth.  It's a rare occurence when these points line up with the correct phases to produce either a perigean spring tide or an apogean neap tide.   

 

The points of perigee and apogee of the Moon are collectively called the Moon apsides (pronounced ap-sid-eez), and are each called an apse.  The line that extends from the perigee and apogee, running the long direction of the elliptical orbit, is called the line of the apsides.  The Sun's gravity tugs on the Moon as it orbits the Earth, which causes the line of the apsides to shift slightly toward the east each month.  This means that, each month, the Moon reaches perigee about 5 1/2 hours later than it did in the previous month. 

 

Astronomers call this motion the anomaly of the Moon's orbit, or the precession of the line of the apsides.  The time between succesive perigees is 27 days, 13 hours and 18 minutes, and is called the anomalistic month.  Okay, I know this makes people's eyes glaze over!  The basic idea is, the Moon does not reach perigee or apogee in the same phase from month to month, and there is a cycle of 8.87 years for the line of the apsides to twirl around one time, so that the perigee and apogee occur in the same places in the constellations.  

 

The word "anomaly" comes from the Greek anomos, which means "lawless."  The word appears a couple times in Scripture, such as:

 

 

However, the anomaly of the Moon is not really "lawless," but is simply one of the many variations that the Moon follows as it traces the path appointed by Jesus Christ, its Creator.

 

Anyway, as the Earth circles the Sun and as the Moon circles the Earth, the line of the Moon's apsides remains pointed in the same general direction, shifting slightly to the east from month to month with the anomaly.  Most of the time, perigee and apogee occur during any phase, so that the they do not significantly add to the tide.  Every so often, all the Moon's cycles converge so that Moon lands at perigee during a Full Moon, resulting in a perigean spring tide.

 

 

 

There are still other factors that contribute to a maximum high tide.  It also depends on the season, and other elements of the Moon's orbit.  We won't bog down on those details.  However, we will note that the solar component to the tide is strongest when the Earth is near perihelion, when the Earth is at the closest point in its orbit to the Sun.  Like the Moon, the Earth and other planets have orbits which are slightly eccentric.  Perihelion is the same idea as perigee, coming from the Greek root helios, which means "Sun."   

 

Perihelion occurs each year on about January 4, when the Earth is 91 million miles from the Sun, about 3 million miles closer than average.  At this time, the Sun's gravity is strongest.  A maximum perigee would occur in early January would result in the greatest sort of perigean spring tide, or the maximum possible high tide. 

 

Anyway, on Saturday, March 19, 2011, the Moon approached perigee within a couple hours of the precise moment of the Full Moon.  As a result, the Moon was the closest it was to the Earth since 1993.  This was reported as the "Supermoon."  At the exact moment of perigee, the Moon was 17,289 miles closer to the Earth than average.  However, this only works about to be about 7% closer than average, not that big a deal. 

 

Therefore, there was no significant "land tide" raised by the Supermoon, and the threats of earthquakes and other such disasters were bogus and overblown.  There was a perigean spring tide that day, but nothing transpired to cause it to make the news.  As we saw, the Moon was slightly larger than normal, and the closeness of the Supermoon simply resulted in a brighter Full Moon than normal.  

 

According to this website, the closest lunar perigee for the period between A.D. 1750 and 2125 was on January 4, 1912, which was a perigean Full Moon that occurred on the same day as perihelion.  No historical correlations of any massive earthquakes are reported from that date.  At that time, the Moon was 221,441 miles from the Earth, only 125 miles closer than last Saturday!

 

As we see, these are tiny differences in the grand scheme of the universe, and nothing to get troubled about.  One interesting thing to note is that, when there is an extreme perigee, there is also an extreme apogee the same month.  The Moon will reach apogee on Saturday, April 2, 2011 when it will be 252,684 miles from the Earth.  However, according to the above website, this is only 40 miles short of the most distant apogee for that same period, which will occur on February 3, 2125!

 

 

As we see, upon examination, the numbers are not really very impressive, and nothing to get all hyped up about.  However, there can be dire consequences to ignoring the effects of the Moon's anomaly on high and low tide.  An infamous example is the Battle of Tarawa in World War II. 

 

Tarawa is an atoll in the Gilbert Islands which was held by the Japanese in the Pacific Theater.  In November 20, 1943, the United States Marines set out to invade and capture Tarawa.  Their landing was scheduled during a neap tide, when the high tide was expected to be lower than normal.  However, the planners failed to take into account that it was an apogean neap tide.  The high tide turned out to be only three feet when five feet was expected. 

 

As a result, the amphibious landing boats ran aground on the reefs, and the Marines had to wade through the water with their rifles over their heads, making easy targets for the enemy.  A thousand Marines were lost in the invasion, and another 2300 were wounded, one of the bloodiest battles of the war.  There are many excellent resources online about the Battle of Tarawa, such as this site.  Had there been a better understanding of Classical Astronomy on the part of the battle planners, the needless loss of American fighting men could have been avoided.