September Equinox 2023 - The Sun Crosses the Celestial Equator

September 23rd marks the equinox, with day and night being of almost equal length. This marks the beginning of fall in the Northern Hemisphere. And although this means it’s time to bid farewell to those long summer days, the upshot for stargazers is longer nights, meaning more time to look up! There are two equinoxes every year, in March and September, when the Sun shines directly on the equator, and the length of night and day are nearly equal. Sun Crosses Celestial Equator The September equinox is the moment the Sun crosses the celestial equator—an imaginary line in the sky above Earth’s equator—from north to south. This happens on September 22, 23, or 24 in most years. Why Is It Called “Equinox?” On the days of the equinoxes, the Earth’s axis is perpendicular to the Sun’s rays, meaning that all regions on Earth receive about the same number of hours of sunlight. In other words, night and day are, in principle, the same length all over the world. This is the reason it’s called an “equinox,” derived from Latin, meaning “equal night.” However, this isn’t entirely true. In reality, equinox days don’t have exactly 12 hours of daylight. Happy September Equinox Everyone! #equinox #sun Images credit: NASA/JPL Music credit: YouTube Audio Library Blue Macaw - Quincas Moreira