WEST WASHINGTON — Did you try balancing an egg upside down today?
Rumors that this is only possible during the equinox may not be true, but what is true is that it begins the brightest six months of the year for the northern hemisphere. The spring equinox arrived at 7:46 a.m. PDT on Friday.
Welcome to spring!
There are exactly two times a year when the sun’s rays shine directly on, or at right angles to, the Earth’s surface at the equator, if it were approached as a flat surface. Those two times are the vernal or spring equinox and the autumn or fall equinox.
There are two reasons for this:
- The Earth orbits the Sun.
- The Earth’s axis is displaced or inclined with respect to its orbital plane with the Sun, that is, the plane of the ecliptic.
Due to the tilted orientation of the Earth along its path around the sun, there is a case where the sun’s direct rays cross the equator from south to north. This is the spring equinox. Thus opening the door to greater entry of sunlight into the northern hemisphere over a period of six months.
Equinox, derived from the Latin terms for “equal” and “night,” implies equal day and equal night, or 12 hours of daylight and 12 hours of night. But in Seattle, today we have 12 and 11 minutes of daylight.
There are also two reasons for this:
- The sun’s rays refract or bend through Earth’s atmosphere in a way that favors a few more minutes of daylight.
- The sun appears as a disk in the sky, rather than a point. Sunset is defined as the moment when the final edge of the sun passes over the horizon, a few moments after its center, giving us a few more moments of daylight. The same effect occurs, but in reverse, during dawn.
The day with exactly 12 hours of daylight is called equilux, and in Seattle, that was around St. Patrick’s Day.
Whichever way you look at it, spring is officially here. Make it worth your while and enjoy it!
Happy spring!
