We have two major ways to divide the year: the Equinoxes and the Solstices. These are events coinciding with specific details about the Earth’s orbit and they’re used as the basis for when each season begins. The Spring Equinox just passed us, on March 20th. Let’s look into exactly what that means.
Orbital Movement of the Earth
The Earth’s movement through space is a little more complicated than just going in one big circle. Our great, big blue marble:
- Rotates around its Axis
This creates the days. One side faces the sun, the other is in shadow.
- Wobbles back and forth on that Axis
This plays a role in creating the seasons. The wobble causes the Summer in the northern part of the world to be warm, while it becomes cold in the southern part. And vice versa for the winter.
- Moves around the sun in an uneven circle (elliptical orbit)
This is where we derive Years from. 1 orbit of the sun is 1 year. This doesn’t break down exactly into an even number of days, which is why we have Leap Years.
These movements ultimately work out two 4 major things: the longest day of the year is the Summer Solstice in the Northern Hemisphere, the shortest is the Winter solstice. On these days, the Earth’s steady wobble has reached it’s peak. It’s rocked as far on its side as it’s going to move. This movement to the side causes days to be longer or shorter (and therefore, more or less heat, which causes warmer and cooler periods).
The period directly between the Solstices are the Equinoxes. These are the two times a year when the Earth’s wobble is essentially perfectly even. The day will be the same length in the Northern Hemisphere and the Southern Hemisphere. You can most easily observe the Equinox at the Earth’s equator, on that day, the sun will be exactly above the equator. If you charte the sun’s position over time, you’d find that it doesn’t follow the same path every day (because of the Earth’s wobble). On one day it may rise just a few degrees to the north or south, but on the equinox, it’ll pass directly above the Equator.
Relevance to Business
The Equinoxes can be used as a handy way to keep track of the upcoming weather, daylight, and the habits of your customers and workers. When you’ve hit the Equinox, it’s fairly easy to say you’re halfway to Summer. The Daylight around the Earth is exactly even at this point. We all know that Spring and Summer mean longer days, but there’s something to be said for planning.
We can walk up to the calendar, point at March 20th, every year and say “we’re halfway to the longest day of the year.” People will start to stay out later. It’s the best time to consider extending your business hours or implement changes involved with increased foot traffic. Around now is when your heating system will finally start to get a break after a long, hard winter.
In a bigger-picture view, the Equinox is also the day you should avoid relying on satellite based services. The sun’s position directly over the equator will put it in line witn a number of satellites, where it’ll typically completely overwhelm their broadcast signals and ground based receivers. We’ve never tested it, but it’s probably enough to even mess with GPS signals.