Wednesday of this week (September 22nd) is the September equinox — we call it the autumnal or fall equinox in the northern hemisphere, but in the southern hemisphere it’s the vernal or spring equinox. The autumnal equinox is (in astronomical terms) the first day of fall, just as the vernal equinox is (in astronomical terms) the first day of spring.
❡ Little lessons: “‘Vernal’ and ‘autumnal’ are wonderful words. Let’s look them both up in our big dictionary.”
Whenever you’re investigating things temporal or calendrical, timeanddate.com is always a good place to start:
The seasons occur because the earth’s axis of daily rotation is not quite perpendicular to the plane of its annual orbit around the sun (the axis is tilted by about 23º). The two solstices occur at the points in the annual orbit when the earth’s axis of rotation is tilted most directly away from the sun (in December, on the first day of northern-hemisphere winter) and most directly toward the sun (in June, on the first day of northern-hemisphere summer). The two equinoxes, in March and September, occur when the earth’s axis of rotation is “sideways” to the sun (so to speak), making the intervals of daylight and darkness equal (or very nearly so). Equi-nox means equal-night (and day).
NASA has a fun educational crossword puzzle for kids that’s filled with seasonal vocabulary — solstices, equinoxes, and more.
You can print out your own copy at NASA’s “For Educators” website. And you can find many more technical facts and figures about solstices and equinoxes on page 385 in your recommended homeschool almanac.
What calendrical events and astronomical alignments will you be marking in your homeschool this Cygnus Term? 😊
❡ Watchers of the skies: Teaching your students about the seasons and the stars is one of the simplest and most enduring gifts you can give them. Your recommended River Houses astronomy guide has descriptions and maps of all the constellations that point out the seasonal highlights, and the astronomical section of your recommended world atlas has beautiful large charts of both celestial spheres. Find a dark-sky spot near you this month and spend some quality homeschool time beneath the starry vault. 🔭
❡ Here, said the year: This is one of our regular posts on Homeschool Astronomy and also on Homeschool Terms & Calendars. Add your name to our weekly mailing list and get great homeschool teaching ideas delivered right to your mailbox all through the homeschool year. 🍂 ⛄️ 🌷 ⛱