The Change of Seasons is Upon Us

September 22, 2008 is the first day of autumn for those of us in the Northern Hemisphere, and the first day of spring for those in the southern hemisphere. What this means is that the weather is going to start changing (if it hasn’t already) for everybody in the mid-to-upper latitudes (and those of you in the equatorial climates are probably wondering what the big deal is). The north pole is headed into a time of twilight and darkness, while the south pole will be enjoying more sunshine. In the north, our days start getting much shorter and in the south, the days start getting longer. Finally, on the equinox, the Sun is positioned directly over our equator (the Sun’s apparent position).

I always look forward to autumn because where I live, it’s got some of the nicest weather of the year (not too hot or muggy, not too cold).  The leaves are starting to change colors, and anywhere that deciduous trees and ornamental bushes grow, you can see some gorgeous colors.

In New England (and the Rocky Mountains, where I grew up), fall color time is also prime tourist time. I suppose that’s true anywhere that colors change.  I remember a few years ago, we went to South America (I was doing astronomy lectures on a cruise ship) in mid-March. When we got to the extreme southern tip of Argentina, the forests had already started to show colors like we see each year in New England. It was quite a treat to see autumn in March!

Stargazing-wise, autumn means increasingly longer nights, which is good. But, they’re colder nights, which means bundling up. For us in the northern hemisphere, autumn’s stars are lovely preview of what’s to come in winter. And, if I stay up late enough at night, I can start to see some of my favorite winter-time constellations (the early risers, anyway).

So, here’s to the change of seasons, no matter where we are!