Spring Is Getting Shorter, But Summer Is Getting Longer

By Debra Kelly on Wednesday, March 23, 2016
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“Fair-handed Spring unbosoms every grace: / Throws out the snowdrop and the crocus first.” β€”James Thomson, “The Seasons, Spring”

In A Nutshell

Spring is getting shorter—by 30–60 seconds every year—and summer’s getting that extra bit of time. Summer is already the longest season. The time shift all has to do with the wobble of the Earth on its axis and the point where the planet reaches its perihelion. The change is nothing new. At one time, a day as 21.9 hours long and a year was around 400 days long. We’re on pace to lose a whole day of spring by the year 3000.

The Whole Bushel

Springtime is an almost universally welcome time of year. Depending on where you live, it’s a reprieve from freezing cold and snow, or it signals the end of a dreary, damp darkness. But if spring is your favorite season, you’ll be in for a bit of a disappointment—if you live long enough to notice it, that is.

Spring is getting shorter ever year by anywhere from 30 seconds to an entire minute.

In 2015, spring’s official start time in the US was March 20 at 6:45 PM (EDT). That’s determined by the US National Weather Service, and it’s the exact moment when the Earth reaches its vernal equinox. The change of the seasons is measured at exact times during the precise moment of the summer solstice, the autumnal equinox, and the winter solstice.

And the seasons definitely don’t divide the year equally. In 2015, spring was 92.76 days, winter was only 88.99 days, autumn was 89.84 days, and summer was the longest season, clocking in at 93.65 days.

The trend will continue, with spring and autumn getting shorter, and summer and winter gaining the time they’re losing.

Summer is longer than winter because of the planet’s distance from the Sun through that season, which impacts how fast we’re traveling. At the aphelion—the point in the orbit where we’re farthest away from the Sun—we’re also traveling the slowest, making the seasons last longer. And we’re wobbling along as we go. That wobble is shaving a minute or so off the length of spring.

Spring is its shortest in the years when the planet hits the perihelion (the point in the orbit closest to the Sun) at the exact mid-point of the season. It’s been getting progressively shorter for thousands of years, and it’ll eventually start going the other way again.

But before then, in the year 3000, the difference will be enough that we’ll lose almost a whole day of spring.

The length of the seasons isn’t the only thing that’s changing, and research scientists from NASA have been looking at the prehistoric terrestrial record to find out more about how the length of the days, seasons, and years have changed throughout the planet’s history. Layers of rock and sediment deposited by daily tides have shown that 620 million years ago, a day was only 21.9 hours long and a year was likely around 400 days long.

Some corals grow in cycles that mean they add a band for every day-night cycle they go through; ancient ones have told us that 350 million years ago, a year was 385 days long.

And if a 30- to 60-second loss of spring seems like an oddly exacting number, that’s nothing. When looking at astronomical measurements recorded by ancient scribes in China, researchers have been able to turn back the clocks to see just how quickly our planet has changed its alignment and its speed. Based on records from 1200 BC, we know that today’s night-day cycle is 0.047 seconds longer than it was then.

Show Me The Proof

LiveScience: Why Spring Gets About 30 Seconds Shorter Every Year
Nature World News: Why Spring is Shorter Than Ever This Year
Scientific American: Fact or Fiction: The Days (and Nights) Are Getting Longer
The Guardian: Spring is 30 seconds shorter every year