Declination Lines

This picture was taken October 23, 2023. The Zodiac sign Scorpio begins this year on October 23rd, so the shadow is on the declination line dividing Libra (green) and Scorpio (blue). The gnomon shadow will track along this line all day. Time on the hour is read on the right side of the figure 8 analemma from the criss-cross (about August 30) until the December Solstice (12/21). Since it is still Pacific daylight savings time (PDT), and the shadow is just underneath the 10 AM analemma, it is 10 AM. The picture was taken at 10:00:19.

August 23rd is the date the Zodiac sign Leo ends and Virgo begins. To see a time-lapse video of the dial’s shadow tracking the 8/23 declination line between Leo (orange) and Virgo (yellow), go to the Home Page and click on the link below the photo or go to the Videos post. Time is read on the left side of the figure-8 analemma (note 8/1 marker is on the left side and the criss-cross will not occur until around 8/30) and an analog clock confirms the accuracy.

Declination is the angular distance of a point north or south of the celestial equator. The celestial equator is the projection of the plane of the earth’s equator into space. For all locations on earth, the sun’s declination is 0 degrees on the equinoxes. Declination of the sun varies between -23.44 degrees on the December Solstice to +23.44 degrees on the June Solstice. Declination is not to be confused with altitude, which is the height of a celestial object above the horizon, measured in degrees.

The declination of the sun on October 23rd is approximately -12.5 degrees. The declination of the sun on August 23rd is approximately +10.5 degrees. The declination of the North Pole is +90 degrees. The declination of Polaris is +89 degrees, 15 minutes, 51 seconds.