In 2023, the Northern Hemisphere’s summer time solstice – and Southern Hemisphere’s winter solstice – falls on June 21, 2023, at 14:58 UTC (that’s 9:58 a.m. in central North America; translate UTC to your time). Learn extra about the June solstice, here.
Longest sunsets in June and December
Right here’s a pure phenomenon you won’t have imagined. That’s, the longest sunsets occur across the time of the solstices. We’re speaking about what number of seconds it takes for the physique of the sun to sink under your western horizon. Sunsets take an extended time round solstices, and a shorter time round equinoxes. It’s true whether or not you reside in Earth’s Northern or Southern Hemisphere.
As seen from each the Northern and Southern Hemispheres, the sun rises and units farthest north on the June solstice and farthest south on the December solstice.
Now think about that the farther the sun units from due west alongside the horizon, the shallower the angle of the setting sun. Which means an extended period for sundown on the solstices.
In the meantime, at an equinox, the sun rises due east and units due west. Which means – on the day of an equinox – the setting sun hits the horizon at its steepest potential angle.
Longest sunsets are how lengthy?
The sundown period varies by latitude. However let’s simply think about one latitude – 40 degrees north – the latitude of Denver or Philadelphia in the USA, Sardinia within the Mediterranean, or Beijing in China.
At that latitude, on the day of a solstice, the sun units in about 3 1/4 minutes.
That’s half a minute longer than the sundown on the identical latitude on the day of an equinox. The equinox sun at 40 levels north latitude units in roughly 2 3/4 minutes.
At extra northerly temperate latitudes, the sundown period is bigger; and at latitudes nearer to the equator, the sundown period is much less. Close to the Arctic Circle (65 degrees north latitude), the period of a solstice sundown lasts about quarter-hour. On the equator (0 levels latitude), the solstice sun takes slightly over 2 1/4 minutes to set.
No matter latitude, nevertheless, the period of sundown is all the time longest at or close to the solstices.
The sunsets are longer in December than June
Because it seems, the sundown and dawn are a tad longer on the December solstice than they’re on the June solstice.
That’s as a result of the sun is nearer to Earth in December than it’s in June. Due to this fact, the sun’s disk looms a bit bigger in our sky in December, and so it takes barely longer to set.
Moreover, the nearer December sun strikes eastward upon the ecliptic at a sooner clip, serving to to decelerate the December solstice sundown (and dawn) much more. For example, at 50 degrees north latitude, the winter solstice sundown (dawn) lasts about 4 minutes and 18 seconds, or about 8 seconds longer than the sundown (dawn) on the summer time solstice.
And now you already know!
Some sunsets from EarthSky Group Pictures
Backside line: Right here’s a pure phenomenon you would possibly by no means have imagined. That’s, the longest sunsets occur across the time of a solstice.
