Astro Bob: Daylight saving time puts spring stars on hold
Advancing our clocks on Sunday, March 12, means we keep Orion in view a little longer at the expense of the spring constellations.
Some prefer year-round daylight saving time. Others can't stand it and want a return to vanilla standard time. I think we can all agree that we're tired of changing clocks twice a year. Speaking of which, be sure to set yours ahead today or you'll be an hour late to work tomorrow.
The old DST-saves-energy argument we were sold years ago is now considered dubious . Studies have found that that the slight decrease in electric lighting from flip-flopping the time is more than offset by increased use of heating and air conditioning.
But you can still make a case for location. Close to the equator daylight time becomes irrelevant because daylight-length varies little across the year. That's why Hawaii sticks with standard time. Arizona is the only other state not on daylight time. It switched back to standard time in 1968 to get rid of that extra hour of sunlight on searing summer evenings, so folks could start cooling off by 8 instead of 9.
Overall, the effects of daylight time in the southern states are less extreme than those experienced by people in the northern states and Canada. For instance, here in Duluth, DST means exceptionally late sunsets (around 9 p.m. or later) in the summer months. Add in lengthy twilights, and the sky doesn't get dark until 11-11:30 p.m., putting a real crimp in star-watching. Without DST, darkness would arrive at a much more reasonable 10-10:30 p.m.
In winter, standard time puts the sun to bed around 4 p.m. and wakes it up again at 8. If we went to daylight time year-round, the winter sun would rise instead around 9 a.m. That seems harsh.
One solution I don't see discussed much would be to compromise and split the difference. Go to permanent DST and advance clocks 30 minutes instead of an hour. India, Iran and parts of Australia do this. Not only would this lessen the impact on our own biological clocks but would temper the extremes of winter and summer sunrise and sunset times.
For now we're stuck with the current daylight time arrangement. By Sunday evening, March 12, you'll notice that (evening) daylight definitely gets a boost, with the sun setting around 7 p.m. instead of 6. Monday morning, the sun will poke over the horizon around 7:30 a.m. instead of 6:30.
Daylight time also affects the stars. All the stars in the western half of the sky (which behave like the evening sun) set an hour later. Those in the east (like the morning sun) rise an hour later. For example, on March 11, Orion stood noticeably west of due south at 8 p.m. local standard time. On March 12 at 8 p.m. local daylight time, it's closer to due south and considerably higher in the sky. Changing to DST delays the exit of the winter constellations. Similarly, it delays the arrival of the spring groups.
Every winter I anticipate the first sight of the bright, orange star Arcturus (located beneath the Handle of the Big Dipper) during the evening hours as a sign of the coming spring. A couple nights ago it twinkled between the trees around 9:30 p.m. Thanks to the time change I have to wait until 10:30 to get my vernal fix. That stings a little. Add in the 14 inches of snow that fell on March 11-12, and it feels like the new season still remains elusive.
I hold onto hope though, remembering that Earth's tilted axis and the planet's yearly journey around the sun will soon make everything right.