NOAA Satellites Monitor the Onset of Spring from the Sky

Note to Screen Readers: This page utilizes an iframe for the content area, which may not be accessible with your screen reader. For screen-reading purposes, Spring has officially arrived in the Northern Hemisphere, while autumn has commenced in the Southern Hemisphere! The vernal equinox, marking the beginning of astronomical spring, took place today, March 20, 2025, at 5:01 a.m. EDT, and NOAA satellites captured a stunning view.

The changing of the seasons occurs at different times due to the Earth's axial tilt of 23.5 degrees as it orbits the sun. This tilt causes the two hemispheres to receive sunlight at different angles, resulting in varying lengths of daylight over the course of the year. During the equinoxes, Earth's axis is positioned neither toward nor away from the sun, creating nearly equal durations of daylight and darkness across the globe. The term "equinox" derives from two Latin words: *aequus* (equal) and *nox* (night). The vernal and autumnal equinoxes are the only times when the sun rises due east and sets due west in nearly all locations worldwide. The stunning imagery above, produced by NOAA's GOES East (GOES-16) satellite, illustrates how the seasons have transformed over the past year. This animation was created by compiling one daily image from the satellite, captured at the same time each day (11:50 UTC), and looping them together.  *Download Image* NOAA's geostationary satellites, GOES East and GOES West, enjoy a remarkable perspective on seasonal changes from their vantage point 22,236 miles above the equator. Orbiting in sync with Earth's rotation, they consistently monitor specific regions over time. This capability allows them to track the terminator—the line that separates day from night—as it shifts throughout the year. During an equinox, this line runs directly north to south over the equator, serving as a vivid marker of seasonal transition. However, the length of day and night is not perfectly equal during an equinox. This discrepancy results from atmospheric refraction, which bends light rays, making the sun appear slightly above the horizon when it is actually below it. Additionally, longer daylight hours occur at higher latitudes, as the sun takes more time to rise and set.  While astronomical spring commenced on March 20, meteorological spring started on March 1. Astronomical seasons are determined by Earth's position relative to the sun, whereas meteorological seasons align with annual temperature cycles and the calendar. Meteorological seasons begin on the first day of months that encompass the equinoxes and solstices. Therefore, meteorological spring began on March 1 and will conclude on May 31. Astronomical spring will officially end, transitioning to astronomical summer on the summer solstice on Friday, June 20, at 10:41 p.m. EDT.

The GOES East geostationary satellite, also referred to as GOES-16, monitors most of North America, including the contiguous United States, Mexico, Central and South America, the Caribbean, and the Atlantic Ocean up to the western coast of Africa. Its high-resolution imagery provides excellent visualization of severe weather events, including thunderstorms, tropical storms, and hurricanes.
Source@NESDIS