Vernal Equinox 2018: Satellite Sees First Day of Spring

The National Oceanic and Atmospheric Administration (NOAA) celebrated a crisp start to spring today (March 20) in the Northern Hemisphere with a stunning view of Earth from sunset to sunrise.

NOAA officials tweeted the view of sunset on March 19 through sunrise March 20, taken with the agency's GOES-East weather satellite.

"Happy Spring #Equinox and happy #firstdayofspring!" NOAA officials wrote. "Today the length of night and day are nearly equal. The days will now become longer at the higher latitudes because it takes the sun longer to rise and set."

The vernal equinox occurs as the sun passes over the equator from Earth's perspective and the Northern Hemisphere begins to tilt toward the sun, leading to longer days in the north and shorter days in the south. It marks the north's first day of spring — snowy weather in some areas notwithstanding — and the beginning of fall for those in the Southern Hemisphere. While the day-to-day variations in weather are much more complex, the vernal equinox is a sign that warmer days are on the way.

The next big sun event for the Northern Hemisphere is the summer solstice on June 21, the longest day of the year, when Earth's northern half is most directly tilted toward the sun. (It's also the south's winter solstice.)

Even better views are coming. NOAA launched what will be the new GOES-West spacecraft this month in partnership with NASA; the eagle-eyed satellite will help track extreme weather across the western United States and eastern Pacific Ocean as a counterpart to GOES-East. The satellite will move to its final GOES-West vantage point after about six months of preparing its instruments and running checks.

To see more NOAA imagery taken today, readers can visit https://www.nesdis.noaa.gov/content/imagery-and-data.

Email Sarah Lewin at slewin@space.com or follow her @SarahExplains. Follow us @Spacedotcom, Facebook and Google+. Original article on Space.com.