MAR 15, 2010 - Earth's Orbital Parameters is a NASA resource I ran across while trying to determine the ecliptic longitude of Earth's perihelion (closest approach to the Sun) over long periods of time. Who cares? Anybody interested in climate change, for one thing. The closest approach is currently early in January, which makes winters shorter and summers longer in the northern hemisphere - which is where most of the land surface of our home planet is. This in turn means that there's more surface heating going on down here. Add in some increased solar radiation, and some greenhouse gases, and you've got yourself a fine rationale for completely overhauling the energy economy which is the basis of modern civilization . . . except that cutting greenhouse gas emissions won't change the orbit, won't change the Sun's output. Pop in the figures for yourself, using the nifty free online application at Earth's Orbital Parameters to produce a table of Earth's orbital eccentricity and obliquity, plus the longitude of perihelion in degrees. You'll have to convert the perihelion longitudes to the more familiar sign-degree-minute format, but that's no big deal. (E.g., the perihelion for the year 2000 is at 282.895 degrees, which is 12° 53' 42" Capricorn.) You can also use this information to account for the frequency of various astrological functions, such as solar conjunctions for example; which are more common when Earth is at or near aphelion (moving slowly) and less when closer to perihelion (moving faster).
