When I awoke this morning, I heard that spring would officially arrive at 7:02 am.  Yes! Because I don’t have an exercise class scheduled on Wednesday evenings, I decided to visit the UMass Sunwheel for the 6 pm informational program.  All day, the sun went in and out of the clouds, but the sky was clear when I left work at 5.  About thirty of us braved the chill and lingering snow to gather around Professor Stephen Schneider of the UMass Astronomy Department.

The Sunwheel, Professor Schneider explained, is a teaching tool in the 21st century, but for thousands of years this type of physical arrangement of markers had been used by many cultures as a calendar, in places as far-flung as England, Egypt, and South America.  It isn’t even that difficult to set up: one simply has to observe where the sun rises and where it sets.  In fact, that is how the UMass Sunwheel was constructed, by patient and careful observation (and plenty of help in transporting and placing the heavy granite stones).

At the Equinox, the sun rises due East and sets due West, the only days in the year that this is true.  All over the world on this day, the citizens of our planet experience 12 hours of daylight and 12 hours of night.  However, the movement of celestial bodies, or at any rate, the appearance of such movement, is place-specific, which means that the angles of the sun in the sky that we observe in Amherst are specific to our latitude (42.3804° N).  Because our latitude is almost half-way between the Equator and the North Pole, we see the sun at its highest point today at 48 degrees above the southern horizon.  At the North Pole on this day, the sun would be observed traveling from east to west on the horizon at 0 degrees, and at the Equator on this day, the sun would be observed traveling at a 90 degree angle to the horizon; at noon, it would be directly overhead.

Although it wasn’t the focus of today’s program, Professor Schneider also told us a little bit about the Moonstones; by their position relative to the Sunstones, we can infer that the moon has a bigger tilt than the Earth, by about 5 degrees.  The newest stones are the two Starstones, placed to indicated the rising of Sirius and Aldebaran.  The stone below is one of them, but I’m not sure which.

By this time I was shivering from the cold, but I did wait to see the sun sink beneath the horizon.  I took this picture at an angle because I didn’t want to stare directly into the sun.

Here’s my final photo, taken from where I had parked my car.

Welcome, Spring!