Just a few days ago was the vernal, or spring equinox. On that day in March, of course, the night is exactly as long as the day. Six months from now is the autumn equinox, when, once again, the night ...

have the same curve only shifted along the x-axis have an amplitude (half the distance between the maximum and minimum values) of 1 have a period (size of one wave) of 360˚ ...