Today, spring has sprung: At 6:45 pm EDT, the Earth’s titled axis will point neither away from the Sun nor toward, marking the vernal equinox and the official start of spring for the Northern Hemisphere. This year we have exactly 92.76 days of spring to enjoy before summer arrives, reports Laura Geggel for Livescience.com. And good news for the lovers of summer — it comes about 30 seconds earlier than it did last year.
That extra half-a-minute we get for summer sun (or thunderstorms) means we have that much less time to enjoy spring’s blooms. Spring has been getting shorter every year for thousands of years, thanks to a wobble in the Earth’s axis. The wobble, called precession, means that Earth arrives the point in its orbit where the Northern Hemisphere is tilted toward the Sun the most — the summer solstice — a bit earlier every year.
At the same time, the Earth is orbiting around the Sun in an ellipse. This slightly squashed circle shape means that our planet moves faster when it’s closer to the Sun and slower when we are farther. That speed change makes winter go quickly and summer go slower. (Sorry, residents of the Southern Hemisphere — for you that means that winter is slower and summer is faster.) That’s why summer steals its seconds from spring. Also, fall is getting longer as winter gets shorter.
The interaction between the Earth’s wobble and its varying orbital speed means that spring won’t get shorter forever. Geggel spoke to amateur astronomer Larry Gerstman to help explain:
Over thousands of years, the shift in the time of the vernal equinox becomes more apparent. For instance, spring will be shortest in about the year 8680, measuring about 88.5 days, or about four days shorter than this year's spring, Gerstman said. (After that point, spring will lengthen again.)
Don’t worry much about the change, unless you are an astronomer. The average person living day-to-day won’t notice that spring is getting shorter. They are far more likely to notice earlier blooms and warmer days sooner in the season thanks to climate change.