Spring has been getting shorter for thousands of years, but unless you've sat down with an atomic clock and an eye to the skies, you probably haven't noticed. While the first day of spring was marked by the vernal equinox Friday, spring is losing time to summer in the northern hemisphere, and will continue to do so for millenia, astronomers say. This year the vernal equinox occurred at 6:45 p.m. EDT on March 20, at which point the Earth's axis reached a halfway mark and the sun bathed both the Northern and Southern Hemispheres in an equal amount of light, the NWS said. From this point until the summer solstice on June 21, daylight will grow in the Northern Hemisphere and shrink in the Southern Hemisphere.
Next year, however, the solstice will come earlier because the Earth wobbles (called precession) on its axis as it orbits the sun, taking a chunk out of spring in the process. As asronomer Larry Gerstman told LiveScience, summer is the longest season this year at 93.65 days. Spring is next at 92.76 days, followed by autumn and winter at 89.84 days and 88.99 days, respectively. By 8680, spring will have shrunk to 88.5 days – or over 6,500 years to lose four days. Bad news if you were looking forward to witnessing the change firsthand. "It's not something that anyone is going to notice unless you're an astronomer or a paleoclimatologist," Goddard Institute director Gavin Schmidt told LiveScience.
http://www.weather.com/science/news/spring-shorter-vernal-equinox-season
No comments:
Post a Comment