Zodiac: The sun, a yellow sphere in the center of the image, points at the stars (in white) and the constellations (in green). The Earth is orbiting around the sun in a red circle. Learn more Tidal forces from the sun cause Earth’s axis to wobble over a 26,000-year period. The wobble changes where in Earth’s orbit the solstices and equinoxes occur. Image via NASA/ Wikipedia. Learn more There is a red line in the middle of an image full of stars (in yellow and white) and constellations (in green and blue). The red line starts with a -4000 on the left and continues to the right as it follows: -3000, -2000, -1000, 0, 1000, 2000. Learn more