Day length chart

Today's nature calendar task:

Add to the table started March 15th. What changes? Sun rises? Sun sets? Length of day? Difference?

Sunrise: 7:17
Sunset: 7:33
Length of day: 12 hours, 15 minutes

I discovered that the day we had exactly 12 hours of daylight and 12 hours of darkness was not March 20th, the first day of spring, but March 17th. I don't know why that is. It would be neat to graph the changes in day length.

I also looked at June to see how long the longest day would be. It was 15 hours, 26 minutes. At that time, the day length changes very slowly. From June 16th to the 25th, the day length is the same. Right now the day length is increasing by about 3 minutes a day.