Analemma

This is the time of year, for me at least, when winter starts feeling overwhelming. I should clarify — winter feels overwhelming to me the moment the first cool breeze signals the end of summer. Autumn is my favorite season, but it is surrounded by my two least favorites, and there is a bitterness to the passing of time that I feel most acutely in autumn. I try to enjoy summer, but the humid heat of New England causes a particular kind of throbbing migraine, with black spots in front of my eyes that resemble a lunar eclipse. And I try to be cheerful about winter, but each afternoon around 3:30, the realization that the sun is dipping toward the horizon causes my heart to sink. I am surprised every time, like a child who is told to do her homework, even though this happens every day. “Not again?!” Somehow I thought today would be different. I don’t know where my spirit gets this fruitless hope.

Maybe because the days are getting longer. The one redeeming thing about winter (alright, there’s Christmas and hot chocolate and snow angels and all of that, too) is that the second day is longer than the first, and so on. The earth sneaks in the shortening days while I am too busy basking in the blazing glory of yellow oaks, red maples, and dry, 60 degree days (in heaven it will be t-shirt weather during the day and just chilly enough to snuggle into a sweater at night) to notice, and by the time the last leaf has fallen and the “wind-chill factor” starts requiring knife metaphors we are inching slowly back toward the sun.

But too slowly. Sunset will not be back to 5 p.m. until February 3rd in Boston, and for a 6 p.m. sunset we have to wait for daylight savings time on March 13th. It is not even January 13th yet. That is a long time to wait. But still much better than the previous daylight savings, would have been April 3rd. To all the early risers who would have preferred to keep that hour of sunlight in the morning, I apologize for my joy. Unnervingly, Congress, “retains the right to revert to the prior law should the change prove unpopular or if energy savings are not significant.” So you may get your hour back after all. But for now, it is MINE.

Another way I obsessively watch the progress of winter is by the historical average daily temperature. Today, for Boston, it is 37. On January 12th, it drops to 36 for the rest of January. The first two weeks of February, when the sunset is crawling past 5 p.m., it lingers at 37 and 38. By the end of February, it is up to 42. Of course this has very little to do with the actual weather (and completely ignores the biting Boston winds), and any given day in February may well be colder than any given day in January. But they are numerical evidence that January and February follow a pattern toward warmth and light.

Here is some more evidence, and the word of the day: Analemma. An analemma is, “a curve representing the angular offset of a celestial body (usually the Sun) from its mean position on the celestial sphere as viewed from another celestial body relative to the viewing body’s celestial equator.” What this means is that if you take a picture of the sun every day (or every n days), in the same location, at the same time every day for a year, then superimpose those images, the sun will make a figure eight. Here is one done in Veszprem, Hungary by Tamas Ladanyi (copyright his).


analemma Hungray

Click here to see the picture on the APOD (Astronomy Picture of the Day) website, run by Robert Nemiroff and Jerry Bonnell.

Advertisements

Leave a Reply

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out / Change )

Twitter picture

You are commenting using your Twitter account. Log Out / Change )

Facebook photo

You are commenting using your Facebook account. Log Out / Change )

Google+ photo

You are commenting using your Google+ account. Log Out / Change )

Connecting to %s