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.
God of the morning, at whose voice
The cheerful sun makes haste to rise,
And, like a giant doth rejoice
To run his journey thro' the skies;
From the fair chambers of the east
The circuit of his race begins,
And without weariness or rest,
Round the whole earth he flies and shines.
- A Morning Hymn, Isaac Watts
IN THIS UPDATE
See the Earth's Shadow
Signs of Spring, 2021
Hope everyone is enjoying the beautiful spring weather. Many thanks to everyone who joined the new Classical Astronomy group at MeWe. We now have about 500 members. Thanks for joining a social media platform that supports free speech and American freedom. It's a sleepy site and neither I nor anyone else is very active. But
it's so liberating to be free of addictive "legacy social media" and its hypnotic algorithms designed to monopolize your time and attention while the bad guys datamine your personal business.
WEBINARS - Thanks to everyone who participated in our recent webinar. Out of a list of 4000 subscribers, 40 expressed interest in the webinar and 14 actually participated. Check out the webinar playback, Evening Constellations for April, 2021. The content is still mostly
valid, except the evening stars have now advanced about 1/12 of a sky rotation from last month, and Orion has now mostly disappeared from the sky for the summer. But this content is still relevant for learning many other current constellations and will help with understanding the topics in this newsletter.
That first webinar was our "rookie outing" and we learned a few things about hosting such online events. We plan to do at least two more webinars sometime in the near future. Please use our online contact form if you would like to be notified about future webinars.
WONDERFUL NEW BOOK FOR HOMESCHOOLERS - I encourage everyone to check out this excellent book, Where God Came Down by Joel Kramer. It's all about Biblical Astronomy and a survey of important sites for events in Scripture. Check out my book review at The Old Schoolhouse. Here's an excerpt:
Where God Came Down is an excellent introduction to the subject of Biblical Archaeology. If you have been to the movies, you might have the impression that archaeology consists of dodging deathtraps in ancient temples to procure priceless artifacts. But in fact, real-world archaeology entails painstaking, tedious work to excavate historical sites, carefully peeling back layers of dirt
and rock accumulated over centuries. A careful analytical process is required, worthy of crime scene forensics, to draw historical inferences from the foundations of ruined structures and the bits of debris uncovered thereby. But the effort pays off in what can be learned of the ancient past.
I encourage everyone to read this wonderful, beautiful book. Please share this review with homeschoolers and any other potentially interested friends.
NOTE!!! Stay tuned since I expect to produce another newsletter in the next week or so to inform everyone about the upcoming lunar and solar eclipses visible from the USA in and May and June, 2021.
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.
See the Earth's Shadow
(The following is an excerpt from Measuring the Heavens, the upcoming sequel to our Signs & Seasons curriculum.)
During the early part of civil twilight, it’s actually possible to see the Earth’s shadow rising up in the eastern sky after the sunset. Within minutes after the Sun has gone down, the Earth's shadow appears as a dark portion of the sky in the east, opposite the position of the sunset. A flat, treeless, unobstructed horizon is required to see the shadow, and it is not readily visible in mountainous
In the early twilight, as the sunset sky is still orange, the Earth’s shadow is seen as a curved arc or a "bow" climbing up above the eastern horizon. The shadow arc is a dark wedge that runs over 180 degrees of the horizon, clearly higher in the middle than at the ends, between about 3 and 5 degrees above the horizon. The Earth’s shadow is centered on the antisolar point, the opposite position in the
sky from the Sun. The Earth’s shadow is very subtle, but has a definite grey color, darker than the surrounding blue of the early twilight sky. Above the shadow is the “Belt of Venus,” which is a ruddy, pinkish ring of sunset glow that circles the horizon.
The Sun’s rays light up the atmosphere above the shadow arc, so that portion of the sky appears brighter. But the Earth blocks the bright Sun’s rays, causing the shadow of the Earth to be cast upon the atmosphere, so that the shadow arc appears as darkness in the sky. The Belt of Venus is an atmospheric backscattering of the red-orange sunset rays which continue out into space beyond the
As civil twilight progresses, and the Sun descends further below the horizon, the Earth’s shadow rises noticeably higher, and the grey arc grows over the eastern horizon. The Earth’s shadow can be seen until the Sun is about 5 degrees below the horizon. After that, the shadow fades into the gathering darkness and becomes indistinct as twilight deepens. The curved arc of the Earth’s shadow follows the
shape of the globe and is another proof that that the Earth is round.
And now on Earth the Seaventh Eev'ning arose in EDEN, for the Sun Was set, and twilight from the East came on, Forerunning Night; – John Milton
Signs of Spring, 2021
One of my favorite signs of spring in Cleveland, Ohio is when the Sun is sufficiently far north to see sunsets at Edgewater Park, along the shores of Lake Erie. I was there this week and was finally able to spot the bright planet Venus, my first sighting of its current apparition as the Evening Star. Venus was at superior conjunction on March 26, when it was invisibly hidden behind
the Sun on the far side from the Earth's position in its orbit.
Over the last 6 weeks, Venus has been emerging to from behind the Sun and is now at an elongation of about 12 degrees to the east of the position of the Sun. I saw Venus about 15 minutes after sunset, and it was about 7 degrees above the flat horizon of Lake Erie. It shined feebly as a faint spark in the gathering twilight. Venus is in the field of the pic below but too faint to be visible. Though I
didn't stick around for nightfall, it would have brightened considerably in the gathering twilight, but would have sunk closer to the horizon, and setting within a half hour.
You probably won't see Venus anytime soon if you have trees or mountains along your western horizon. But Venus will now quickly rise higher in the evening sky and it should be an easy sight for everyone before Memorial Day. So keep scanning the western horizon above the place of the sunset as night falls in your area.
We'll enjoy Venus as a bright and cheerful visitor to our evening skies all summer and into the fall, through the end of 2021.
Mars is still hanging around the evening sky, and will do so throughout the spring and summer. In case you missed our previous coverage, Mars is readily identifiable as the Red Planet, having a distinct copper color. You'll have an easy time spotting Mars on the evening of Saturday, May 15, when it aligns with the waxing crescent Moon.
After passing Mars, the Moon continues its eastward motion from night to night. As you observe the Moon's waxing phases this month, keep in mind that, when it is a Full Moon, there will be a total lunar eclipse visible before sunrise over North America on the morning of Wednesday, May 26. More info in next week's newsletter.
On the evening of Sunday, May 16, the Moon will have moved away from Mars to align with the twin stars Castor and Pollux in the constellation Gemini. If you don't already know the twin stars, keep an eye on them in the evenings of May and into June. As the Sun draws toward the place of the summer solstice in Gemini on June 21, the twin stars will appear to sink toward the sunset in
the evenings over the next month. This happens every year and is a celestial sign of the spring, just as sure as the return of the robins and the blossoming of the flora.
On the evening of Thursday, May 27, Venus will be joined by the elusive planet Mercury. While Venus is very bright and usually high in the sky, Mercury is always close to the Sun and not very conspicuous amidst the bright glow of sunset. You'll need a flat and cloudless horizon to pick out this conjunction of the inferior planets. (For more information on the cycles of the planets, check
out our Signs & Seasons curriculum.)
By early June, Castor and Pollux have sunk quite close to the horizon in the evening hours after sunset. Venus is gaining elevation and should be an easy object to spot. On the evening of Monday, June 7, Mars will be aligned with these stars, and these three bodues will form a straight line in the evening sky, a very interesting sight.
During the next lunation a month from now in June, the Moon will align with Venus, Castor and Pollux and Mars over three consecutive evenings. The Moon will be in conjunction with Venus on the evening of Friday, June 11. The Moon will make its closest pass to Castor and Pollux on Saturday, June 12. And the lunar conjunction with Mars will occur on Sunday, June 13. This
will be a fun weekend for observing the Moon and the current evening planets.
The Sun reaches its northern annual extreme on the ecliptic on the summer solstice, Monday, June 21. It can be challenging to visualize the celestial orientation of the Sun among the stars of the zodiac. But if we could somehow observe the Sun's position among the zodiac constellations at noon, it might look like this....
On the summer solstice, the Sun is more or less at the "feet" of Gemini, and above Orion, invisibly hiding these stars behind its bright glare. Since the Sun is at its northern annual extreme, it rises and sets at its furthest positions to the north of the year, and thus spends the maximum amount of time above the horizon, resulting in the longest day of the year.
As the summer progresses, the Sun overtakes Castor and Pollux. These stars disappear into the sunset and the constellation Leo now hangs over the place of the sunset into July. This position of Leo is just as much a sign of summer as the long, warm days.
By this time, Mars and Venus will have drawn close to each other. Mars is now sinking into the sunset while Venus is rising higher above the sunset. These planets will "meet in the middle" on the evening of Monday, July 12, the night of their planetary conjunction. But a more interesting sight might be the evening before, Sunday, July 13, when these planets are joined by the waxing
crescent Moon, a beautiful and interesting trio.
And always remember, on any night of the year, Venus and Mars are alright tonight!
So as mentioned above, keep your eyes open for another newsletter in the next week or so, with info about the upcoming lunar and solar eclipses visible from the USA.
Til next time, God bless and clear skies,
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