Photo: The rising Sun, as seen through the Fall Equinox horizon marker at the Giovale Open Deck Observatory.
What is an equinox?
An equinox is the moment at which which the sun crosses directly over the celestial equator, an imaginary projection of the Earth’s equator into space. At these times, which occur twice a year, day and night are of approximately equal length. In most cultures in the northern hemisphere, the equinoxes mark the beginning of spring and fall.
When is the Fall Equinox?
The Fall Equinox occurs around September 20 each year, with slight variations due to the Gregorian calendar’s leap year cycle. The approximate moment of equinox (when the sun is directly over the celestial equator) will occur at 1:30 am UTC (universal time) on September 22, 2020. This corresponds to 6:30 PST on March 19.
How do I observe the Fall Equinox?
On the morning of the equinox (September 22), watch for the sun rising due east on the horizon, marking the shift from winter to spring. In the evening, the sun will set due west. In the coming weeks, you will observe that the arc of the sun is getting lower and lower in the northern ...