Classical Astronomy - Analemma Redux

Published: Mon, 12/15/25

Updated: Mon, 12/15/25

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.

The mighty God, even the Lord, hath spoken, and called the earth from

the rising of the sun unto the going down thereof. -- Psalm 50:1

IN THIS UPDATE

Analemma Redux

Hi Friends,

Hope everyone is doing well and that your Christmas plans are coming together! I already wished you all a Merry Christmas but there's some additional information pertaining to the recent newsletter that should be included.

Before we get to that, I also wanted to share my new article just released in The Old Schoolhouse magazine. Hope you'll give it a read....

A Home Library: for Your Family and for Posterity

35 Years of Classical Astronomy

The years fly by like nothing and today, December 15, 2025, is the 35th anniversary of the day when I was first inspired to begin "the project" which grew into Classical Astronomy. I've told the story several times of how I had a phone call with my friend, Bob McCracken, co-inventor of the atomic clock at the old National Bureau of Standards on December 15, 1990. We discussed different ways of teaching astronomy to kids. After hanging up from that call, God blessed me with the idea of using visual media (cartoons and graphics) to explain visual concepts in the sky. There was nothing like it at the time. Since then we have a whole internet of visual media but I keep plugging along, not sure what else to do with myself. I was almost 30 at the time and now I'm almost a senior citizen. Funny how the years of life evaporate so quickly. Thank you for your interest and support in Classical Astronomy, looking forward to doing this for years to come.

For more information about topics from Classical Astronomy

discussed in this newsletter, please check out

Signs & Seasons,

a homeschool astronomy curriculum

(but popular with adult readers too!)

Check out the Book Trailer video for Signs & Seasons !

Visit our archive of previous editions of the Classical Astronomy Update newsletters, going back to 2007.

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*****

Analemma Redux

No sooner did I send the last newsletter that I remembered a couple interesting things about the analemma that you might recognize. The analemma appears on world globes made by the George F. Cram Company, which operated from 1867 until 2012. Cram globes were a common feature in school classrooms in years gone by. You might have seen one on a globe in your school growing up or maybe you had one in your home like mine, shown here. Analemmas are relevant to navigation since the globe can show the tropical latitudes where the Sun is visible directly overhead at the zenith on certain dates of the year.

In pop culture, the analemma was shown in the excellent movie "Cast Away" with Tom Hanks, where his character marks the daily path of a sunbeam shining onto his cave wall to create a crude calendar. This is not a very accurate-looking analemma, but I was tickled to see this obscure aspect of Classical Astronomy appearing in a high-profile Hollywood movie, even though it likely sailed past most of the viewers.

Here's a very cool video. Someone set up a camera to snap a picture of the Sun every day at the same time. The Sun's daily position traces out the familiar figure-8 pattern of the analemma. Notice how the time stamp on the video "springs forward" to 5:40 PM in the spring and "falls back" to 4:40 PM in the fall. My email newsletter service won't embed videos so click on the pic below to see the video on TwiX.

In response to the last newsletter, I got this great email from Steve in Philadelphia, an amateur astronomer who likes the sky....

I wanted to write again because I have long been fascinated by the analemma, ever since I first saw it on my globe that I got for my 10th birthday. I really appreciate your explanation of it. It really clarifies the astrophysics underlying its shape. Until now I had known only vaguely that the figure 8 shape arises because of a combination of the eccentricity of the earth's orbit and the 23.5 degree tilt of the ecliptic but lacked the detailed understanding that you provided.

At various times over the past 15 years or so I've attempted to measure it. With my latest iteration, I've been tracing the analemma for almost three years. See the attached image, which is my homemade solar observation device. Every sunny day that I'm home at 11:59:19 AM EST (mean solar noon at my longitude), I place this device in a particular location and orientation in my front yard and mark the position of the gnomon's shadow. I've been doing this since January, 2023.

It's missing long periods in Jan and Feb. I haven't been able to collect data for those dates yet due to lack of sunny weather converging with noon conflicts on both Saturday and Sunday. But other than that, I've been able to fill it in pretty nicely. The figure 8 shape is really clear, and it is easy to see that the sun returns to the same position year after year.

At some point I intend to work out the math formulas that would convert the shadow points to the actual sun declination and right ascension at mean solar noon, but haven't taken the time yet. There are two big complications to this: the grid lines do not run perfectly north and south, and the board is not perfectly level. If I ever make a new one I will try to correct for those problems. In the meantime I'm happy with just seeing the analemma traced out.

Most people are mildly interested when I show them, but I figured you'd be especially interested!

Wow! Yeah Steve, I'm especially interested! Is that cool or what? This is what I love about Classical Astronomy. It's real and it's easy to observe and experience if you take a little bit of time out of your day to notice. I give Steve a lot of credit for undertaking this and feel kind of dumb in comparison. I have some perfect south-facing windows here in my office where I could have been doing this for the last 25 years and it never crossed my mind! So like, DUH! And I'm supposed to be the Classical Astronomy guy!

*************ACTIVITY!!!*************

I'd encourage you all to attempt this yourselves. Any fixed spot of sunlight or any shadow viewed at the same precise clock time each day will trace out an analemma over the span of a year. You can use a hole in a window shade that casts a sunbeam on the floor or whatever you can think of. You can put a colorful window cling on a window or hang a jewel or other ornament that shines a colorful spot on the wall or floor. The main idea is to mark the spot with the date at the precise minute each sunny day over the span of the year. Once you create the analemma, you have a calendar that can be used to find the date forever more. The sunbeam or shadow will cross the analemma at the same spot on the same date for years to come. This would be a fun activity with homeschool kids, too bad I didn't think of it when our kids were still at home.

There are old churches in Europe with analemmas, like the Cathedral of St. Alexander of Bergamo in northern Italy. A sunbeam shines through a little hole and shines onto a meridian marker and traces out an analemma. Some pictures are shown in this link and this link, with accompanying text if you can read Italian.

Once again, my family and I wish you and your family a very blessed and Merry Christmas and a prosperous and purposeful New Year in 2026!

Till 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

The Ryan Family
www.ClassicalAstronomy.com

1621 Merl Avenue, Cleveland, OH, 44109, USA

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