31 December 2011 Circling the star, watch your speed!

          Millions of dollars are being spent as cities around the globe launch fireworks skyward in celebration of the planet’s completion of another voyage around the star we call “the sun.”  This orbital completion is easily described as:

          “The sidereal year is the time taken for the Earth to complete one revolution of its orbit, as measured against a fixed frame of reference (such as the fixed stars, Latin sidera, singular sidus). Its average duration is 365.256363004 mean solar days (365 d 6 h 9 min 9.76 s) (at the epoch J2000.0 = January 1, 2000, 12:00:00 TT).

          The earth is revolving around its North/South axis.  At the equator, the circumference of the Earth is 40,070 kilometers, and the day is 24 hours long so the speed is 1670 kilometers/hour ( 1070 miles/hr). This decreases by the cosine of your latitude so that at a latitude of 45 degrees, cos(45) = .707 and the speed is .707 x 1670 = 1180 kilometers/hr. You can use this formula to find the speed of rotation at any latitude.  Simultaneously the planet is orbiting the sun at Average orbital speed of  29.78 km/s   or, 107,200 km/h. 

          The sun and its planets are simultaneously orbiting the center of the Milky Way galaxy.  The Sun lies between 25,000 and 28,000 light years from the Galactic Centre, and its speed within the galaxy is about 220 kilometers per second, so that it completes one revolution every 225–250 million years. This revolution is known as the Solar System's galactic year.  At present, we do not celebrate this event. 

            Given the immense distances in the Milky Way and other galaxies, the possibility that we may never find another sentient species is quite high.  These distances make interplanetary war and intra-galactic war likely to occur only in the pages of science-fiction novels.  

            That provides us something to celebrate here in our own little corner of the universe.  Fireworks are not necessary, just an appreciation for the laws of physics that govern the universe’s functions.  Therefore, to anyone who may be reading the assorted lunacies that I post, thanks for riding along with me, and Happy New Year.  May your 2012 bring you health and happiness.

            Tonight’s menu:  Oven-roasted prime rib roast

                                    Baked russet potatoes

                                    Brussels sprouts braised in heavy cream and nutmeg

                                    Ice cream

                                    Champagne

Lift your glasses!