It seems as if nothing I try to do is ever as simple as it seems. Lately, I’ve been happily reveling in the fact that the days are getting longer, or to be more precise, the amount of daylight in our days is more than it was the day before. So, fool that I am, I decided to quickly look up exactly how much they’ve lengthened since December’s shortest day of the year.
Can of worms. Don’t go there. Not without a scientific calculator, a dictionary, ephemeris and at least a casual relationship with an able bodied seaman, which sounds more risque than it probably is. But I digress. I started with my favorite weather site, Weather Underground. It’s as reliable as these sites ever are and simple to navigate, which is a big plus for me. In the Astronomy section, there was, indeed, an entry for Length of Day. For May 31st, it read 16h 02m and I should have read that and returned to working on the research project that will pay the bills chez Hawkins if I finish it on deadline. But, I didn’t.
Above that entry, there was another that read, “Length of Visible Light 17h 27m. What the heck was this? Was some of the daylight invisible light? And, if so, why? Well, both of those entries were clickable, so I clicked on Length of Day and that’s when I opened the can of worms. Their story is that Length of Day is the time between Actual Sunrise and Actual Sunset. They were mum on how to determine when Actual Sunrise and Actual Sunset occur, so I clicked on Length of Visible Light, foolishly thinking that it might hold the clues to this puzzle. Big mistake.
Length of Visible Light, according to WU, is (and I quote), “The time of Civil Sunset minus the time of Civil Sunrise.” Okaaay. And how, I wondered, do we know when Civil Sunset and Sunset are when we don’t even know WHAT they are? Well, I didn’t see anything on the WU site about Civil Sunrise and Sunset, but I did spy an entry for Civil Twilight, so thinking it might shed some light on the whole thing, I clicked on that and got this definition, “The time period when the sun is no more than 6 degrees below the horizon at either sunrise or sunset. The horizon should be clearly defined and the brightest stars should be visible under good atmospheric conditions (i.e. no moonlight, or other lights). One still should be able to carry on ordinary outdoor activities.”
This didn’t help much with the sunrise and sunset wheeze, but it did draw my attention to two other Twilights, Nautical and Astronomical. As any seaman can probably tell you and ascertain with his sextant, assuming he has it with him in the bar or tattoo parlor, Nautical Twilight is “The time period when the sun is between 6 and 12 degrees below the horizon at either sunrise or sunset. The horizon is well defined and the outline of objects might be visible without artificial light. Ordinary outdoor activities are not possible at this time without extra illumination.” Well, unless you’re catching fireflies or fishing for horned pout or a raccoon investigating garbage cans, that is.
And what about Astronomical Twilight? Well, Astronomical Twilight is “The time period when the sun is between 12 and 18 degrees below the horizon at either sunrise or sunset. The sun does not contribute to the illumination of the sky before this time in the morning, or after this time in the evening. In the beginning of morning astronomical twilight and at the end of astronomical twilight in the evening, sky illumination is very faint, and might be undetectable.”
So, there you have it…whatever IT is. All I know is that today is shorter now, for me, because I wasted so much time trying to find out something that I could have figured out around 3:45 tomorrow morning when the “morning chorus” as Robert Lurtsema of Public Radio used to call it i.e. the thousands of furshluggener birds that lurk outside my open window start yakking at each other loud enough to wake the dead. And me.
Every morning the chorus gets earlier and every evening they say goodnight to each other or have their last word with their mates later and later. Around the middle of June, they’ll start to get up later and go to bed earlier and so will the sun. Me, I’ll still be lying awake right through Civil and Nautical Twilight. But without the birds, maybe I’ll get lucky and fall asleep before Astronomical Twilight rolls around. I can hope.