Saturday is our usual day to post homeschool astronomy notes for the River Houses. On the first Saturday each month we take a glance at what will be happening in the skies in the weeks ahead, and on the second Saturday we post about one of the Great Stars of the northern hemisphere night sky — print your own copy of our monthly star calendar and follow along with us!
Teaching your homeschool students the names of the major constellations and the brightest stars is one of the most enduring gifts you can give them. Most of the brightest stars that are visible to the naked eye have both old vernacular names — Vega, Aldebaran, Sirius, Arcturus, and so on — as well as more formal scientific designations. Some of the vernacular names are derived from Latin or Greek, but many come from Arabic — astronomy is one of the few subjects where English has absorbed quite a few words from Arabic. (The other principal subject is the related field of mathematics.) You can recognize the Arabic origin of many star names by noting how many begin with “Al-”: Alpheratz, Algol, Aldebaran, and so on. “Al” is the definite article in Arabic, equivalent to “The” in English, so Al-pheratz, Al-gol, and Al-debaran are (with some semantic scrambling over time), The Navel, The Ghoul, and The Follower. A good dictionary will typically give you the derivations of the best-known star names (though perhaps not some of the lesser ones).
There are an awful lot of stars visible to the naked eye, however, and giving them all individual names is not practical. Astronomers needed to develop a clear system of star nomenclature that was simple and expandable, and that incorporated within the names themselves some basic information about each star — its brightness and general location, for example.
The German astronomer Johann Bayer (1572–1625) was the one who devised the formal system of star naming that is still in common use today — it’s a system all young homeschool astronomers should get to know, and it will give them a chance to learn a tiny bit of Latin and Greek along the way.
In Bayer’s system, the stars in each constellation, from brightest to dimmest, are assigned a lowercase letter of the Greek alphabet: α (alpha, brightest), β (beta, second brightest), γ (gamma, third brightest), δ (delta, fourth brightest), and so on. (You can find a table of alpha‑bets, including Greek, on page 51 of our recommended homeschool dictionary.) This Greek-letter designation is combined with the name of the constellation in its Latin possessive (genitive) form: Lyra becomes Lyrae (“of Lyra”), Canis Major becomes Canis Majoris (“of Canis Major”), and so on. The brightest star in the constellation Lyra (the star Vega) thus becomes α Lyrae (“alpha of Lyra”), the brightest star in Canis Major (the star Sirius) becomes α Canis Majoris (“alpha of Canis Major”), the brightest star in the constellation Cygnus (the star Deneb, which we wrote about last week) becomes α Cygni (“alpha of Cygnus”), and so on, through all 24 Greek letters and all 88 constellations.
Our recommended backyard astronomy guide includes simplified charts of all the constellations, good for beginners, and on these, as on any professional star chart, you’ll see the little Greek letters next to each star — that’s the legacy of good old Johann Bayer.
What celestial sights and astronomical apparitions will you be examining in your homeschool this Cygnus Term? 🔭
❡ Choose something like a star: Teaching your students to recognize the constellations is one of the simplest and most enduring gifts you can give them. Your recommended backyard star guide and homeschool world atlas (riverhouses.org/books) both contain charts of the constellations that will show you the all the highlights. Find a dark-sky spot near you this month and spend some quality homeschool time beneath the starry vault. 🌌
❡ Star bright: If you’d like some light and easy homeschool astronomy lessons, download and print a copy of our annual River Houses Star Calendar (riverhouses.org/calendars) and follow along with us month by month as we make twelve heavenly friends-for-life over the course of the year. 🌟
❡ Watchers of the skies: This is one of our regular Homeschool Astronomy posts. Add your name to our free River Houses mailing list (riverhouses.org/newsletter) and get great homeschool teaching ideas delivered right to your mailbox every week. 🗞