Today is the December solstice — we call it the winter solstice in the northern hemisphere, but in the southern hemisphere it’s the summer solstice. The winter solstice is (astronomically speaking) the first day of winter, just as the summer solstice is (astronomically speaking) the first day of summer.
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 the earth’s annual orbit around the sun (it’s tilted by about 23º). The two solstices occur at the points in the orbit when the axis 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 is “sideways” to the sun (so to speak), making the intervals of daylight and darkness equal (or very nearly so).
NASA has a fun educational crossword puzzle for kids that’s filled with seasonal vocabulary — solstices, equinoxes, and more.
What calendrical events and astronomical transitions will you be marking in your homeschool this season? 😊