GoKawiilIt's been a long winter, but spring is close. On Friday, the vernal equinox arrives, signaling the astronomical start of spring (and the end of winter!) in the Northern Hemisphere. Though equinoxes might not get the same attention as solstices, they're a lovely way to observe the shifting of the seasons. Let's get to know the vernal equinox, what it is and why it happens.
When does the vernal equinox happen?
The spring equinox has a specific time, occurring at 10:46 a.m. ET/7:46 a.m. PT, on Friday, March 20.
What is the spring equinox?
You've no doubt noticed the lengthening of daylight as winter winds down, especially with the time change this past weekend. The vernal equinox marks the tipping point into longer days.
The word "equinox" comes from the Latin words for equal and night. Daylight and night are roughly equal during the equinox. We experience two each year -- the vernal equinox in the spring and the autumnal equinox in the fall. The word "vernal" traces to Latin and references spring.
Enlarge Image This National Weather Service graphic shows Earth's tilt, how our planet orbits the sun and when the equinoxes and solstices occur in the Northern Hemisphere. NWS/NOAA
The Earth spins on an axis (think of it like a line running from pole to pole) with a 23.5-degree tilt. Some parts of the planet get more direct sunlight than others. That's how we get our seasons, and how it can be summer in the Northern Hemisphere while it's winter in the Southern Hemisphere.
"The spring equinox is when the Northern Hemisphere transitions from being pointed away from the sun (during winter) to being pointed toward the sun (during summer)," says Emily Rice, associate professor of astrophysics at the Macaulay Honors College of the City University of New York. "The tilt is lined up with Earth's orbit for just a moment." That's when we get nearly equal amounts of daylight and night.
How are equinoxes different from solstices?
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