Look up into the daytime sky tomorrow (at 2:30pm GMT to be exact) and the sun will appear 7%-8% larger. The New Year starts us off with Perihelion, the point of closest approach of the earth's orbit to the sun. On January 4, 2006 the earth will be 147.5 million km from the sun, while on July 3, 2006 we experience Aphelion or the farthest point at 152.6 million km away from the sun.
- The phenomena applies to any celestial object in an elliptical orbit. In astronomy, an Apsis (plural apsides "ap-si-deez") is the point of greatest or least distance of the elliptical orbit of a celestial body from its center of attraction (the center of mass of the system).
- Each planet revolves around the Sun in an elliptical path, with the Sun occupying one of the foci of the ellipse (see Kepler's 1st Law of planetary motion)
- Northern summer on earth is 5 days longer than northern winter as planets move more slowly at aphelion than they do at perihelion (see Kepler's 2nd Law of planetary motion)
- Seasonal weather patterns are shaped primarily by the 23.5-degree tilt of our planet's axis, not by the Earth's elliptical orbit. That's why it is not hotter for us Northern Hemispheres in January compared to July.
- The exact dates of Perihelion and Aphelion vary each year as do Equinoxes and Solstices
Labels: science
