This is the Classical Astronomy Update, an email newsletter especially
for Christian homeschool
families (though everyone is welcome!) Please feel free to share this with any interested friends.
Who hath divided a watercourse for the overflowing of waters, or a
way for the lightning of thunder; To cause it to rain on the earth,
where no man is; on the wilderness, wherein there is no man;
To satisfy the desolate and waste ground; and to cause the
bud of the tender herb to spring forth? - Job 38:25-27
IN THIS UPDATE
Vernal Equinoxy - Spring, 2021
Hello Friends,
Happy spring! As mentioned last week, here's a quick little newsletter to get you started for spring. Now that our social media presence is reduced, I plan to create more email newsletters. Feel free to share this with your friends!
Thanks to everyone who joined the new Classical Astronomy group at MeWe! We had about 80 new members this past week. Thanks for joining a social media platform that supports free speech and American freedom.
WEBINARS- Also thanks to everyone who responded expressing interest in Classical Astronomy webinars in the near future. I hope to get a presentation together sometime in the next couple weeks and will contact the respondents directly. If you have not done so, please send an email using our online contact form at the website if you are interested
in participating. Please indicate which evening(s) are good and if there are any special topics you'd like to see presented.
For more information about topics from Classical Astronomy
discussed in this newsletter, please check out
a homeschool astronomy curriculum
(but popular with adult readers too!)
Visit our archive of previous editions of the Classical Astronomy Update newsletters, going back to 2007.
*****
Vernal Equinox
For from the rising of the Sun, even unto the going down of the same my name shall be great among the Gentiles, and in every place incense shall be offered unto my name, and a pure offering: for my name shall be great among the heathen, saith the LORD of hosts. - Malachi 1:11
For those of us in the northern hemisphere, it's clear that the days have grown. The Sun rises earlier in the morning and sets later in the evening, signaling long, warm days to come. And our friends in the southern hemisphere have noticed that the days are growing shorter, as the Sun rises later and sets earlier, indicating darker, colder days ahead.
But March 20 is one of two days in every year when everyone in the entire world can agree on something! March 20 is the vernal equinox, a day when everyone in every location in the world observes an equal period of daytime and nighttime. On the equinox, the days are 12 hours long, as are the nights. For many nations in the northern hemisphere, this day is commonly considered the first day of
spring.
The Celestial Equator
The moment of the equinox is defined as the precise time when the Sun crosses the celestial equator. This is the celestial counterpart to the Earth's equator, a great circle in the sky between the north and south celestial poles. Like the Earth's equator, this celestial circle is neither north or south, but is actually the dividing line between the two. The time of the Sun's equator crossing is the precise moment when spring begins. Today, in 2021, spring began at 5:37AM
EDT.
The celestial equator passes directly overhead as seen from the Earth's equator. So on the equinox, the noon Sun passes through the zenith at equatorial nations such as Equador, Kenya and Indonesia. With the Sun overhead, noon shadows vanish underneath the feet of dwellers of these nations on the equinoxes.
Over the course of the year, the Sun moves from north to south in the sky, causing the changing of the seasons. When the Sun is high in the northern part of the sky, it is summer in the northern hemisphere and winter in the southern hemisphere. And similarly, when the Sun is at its southern extreme, it is summer in the southern hemisphere and winter in the north.
The Sun and the Zodiac
As the Sun moves through the sky each year, it follows a circular path called the ecliptic. This circle is "tilted" or "inclined" with respect to the celestial equator, so that half of this circle is north of the celestial equator and the other half is south. The ecliptic circle falls along a band of constellations collectively called the zodiac. The Sun appears to move across the line of sight of these zodiac constellations, giving the impression that the Sun is passing
through this band of stars. (The zodiac and its true meaning as the cause of the changing seasons is explained in detail in our Signs & Seasons astronomy curriculum.)
The LORD alludes to the zodiac band in this famous passage:
The heavens declare the glory of God and the firmament sheweth his handiwork.... In them he hath placed a tabernacle for the Sun, which is as a bridegroom coming out of his chamber, and rejoiceth as a strong man to run a race. - Psalm 19: 1, 4b-5
The zodiac really is like a "tabernacle" for the Sun. The Sun's apparent motion is due to the actual motion of the Earth in its orbit. So each day, the Sun appears to move to a slightly different place in the zodiac than the day previous, completing a circle in 365 days. So in this respect, the zodiac is like a "tent" or tabernacle for the Sun, since the Sun pitches his "tent" in a new place each day!
Anyway, on March 20, the Sun is lined up with the zodiac constellation Pisces the Fish. In the coming months, the Sun will move through the northern constellations Aries the Ram and Taurus the Bull, reaching its northern limit on the Summer Solstice on June 20, in front of the stars of Gemini the Twins.After that, the Sun will head south again through the zodiac constellations
Cancer, Leo and Virgo as the summer rolls along.
Just like there is a coordinate system of latitude and longitude to locate position on the Earth, there is a counterpart coordinate system on the celestial sphere of declination and right ascension to locate positions in the sky. The point in the sky of the vernal equinox is the starting point of this system, zero declination and zero right ascension. This subject will be
explained in detail our upcoming book Measuring the Heavens, the sequel to our Signs & Seasons astronomy curriculum.
Since the celestial equator is the midpoint between the celestial poles, it crosses the horizon at the midpoints of the sky, at due east and due west. In this way, the LORD established an astronomical foundation for finding these compass points. On the equinoxes in March and September, as the Sun crosses the celestial equator, our bright daytime luminary can be seen rising due west and setting due west. And being between
its annual extremes, neither north or south, the entire world sees twelve hours of daylight and twelve hours of nightime. (Well, almost the entire world! But that's another story....)
The following pictures were taken on March 19. They show the Sun going down nearly due west. The sidewalk and the street run directly from east to west so the Sun can seen rising at setting at opposite ends of the street.
(NOTE TO PARENTS! If you live on such a street, do NOT let your kids stand in the middle of the street, as shown in the pic, without adult supervision and after looking both ways! (But you already knew that! :) ))
The feasts of Passover and Easter occur in proximity to the vernal equinox, based on time of the Full Moon that occurs near this seasonal signpost. We've discussed these topics at length in previous newsletters over the years, which were incorporated into our Signs &
Seasons astronomy curriculum. Check out these articles adapted from these newsletters as published at Crosswalk.com:
((((((((((( ACTIVITY ALERT!!! ))))))))))))))))
(Activity 1)
If you have a flat horizon to the east or west, try to notice the rising and setting of the Sun on the equinox. Many streets in the United States run from east to west. So on the equinox, you can see the Sun rising and setting over opposite ends of those streets. If clear skies permit, try to do the same in your own neighborhood on the equinox.
(Activity 2)
Also, be sure to watch the sunrise and sunset in the coming weeks and months. The Sun will be continuing to move north in the sky, rising and setting further to the north. The northern days will continue to grow longer until the longest day, June 21, also known as the first day of summer.
(Activity 3)
If Mom and the kids are available near "High Noon" in your location, be sure to measure the Sun's changing Noon altitude. Take a tape measure and measure the length of Mom's shadow at noon. As Spring advances and the Sun moves north, the Sun climbs higher in the noon sky, and Mom's shadow will be short. On the equinox, Mom's shadow will be only a little shorter than Mom's actual height. But on the summer solstice in June, Mom's shadow will be maybe a foot long, depending
on where you live.
And in the lands "Down Under," the Sun's Noon altitude will sink lower and lower till the shortest day on the June solstice. Whichever hemisphere you live in, keep a weekly record of your shadow measurements to see how Mom's shadow changes over the season.
(((((((((( URBAN LEGEND ALERT!!! )))))))))))
There's a myth that makes the rounds this season that eggs will stand on their ends on the equinox. This idea has New Age appeal since allegedly "cosmic forces are in balance." Anyway, this is pure nonsense. There are no such "cosmic forces" and the Earth's gravity does not variably operate on only eggs just because the daytime and nightime are of equal length! On any day of year, one can find an
egg that will balance on its end, but this is due to the shape and weight distribution of the egg, not some elusive "cosmic forces!"
Til next time, God bless and clear skies,
- jay
The Ryan Family
Cleveland, Ohio, USA
When I consider thy heavens, the work of thy fingers, the moon and
the stars, which thou hast ordained, what is man that thou art
mindful of him? and the son of man, that thou visitest him?
- Psalm 8:3-4, a Psalm of David
|
|
|
|
