03 January 2018

Earth and Sun Closest

Sun so close yet so cold...Yes Today Sun and earth will be closest to each other at a distance of 14,70,99,586 km. This point of any object closest to Sun is called Perihelion. The reason for the cold in northern hemisphere is due to the orientation of earth's axis and as you can see in the illustration, the Sun is moved to southern hemisphere where they are experiencing Summer now. 

Since earth's orbit is almost circular, at farthest point from Sun which occurs on July 6th the distance will be 15,20,96,155 km. This farthest point from Sun is called Aphelion. The angular size of the Sun which we measure in degrees at perihelion is 0.542018074degrees. And as we know the orbit is almost circular the difference in angular diameter of Sun from Perihelion to Aphelion is very small. At Aphelion the angular diameter is 0.5243709741degrees. 

 If we compare this to Mercury, the perihelion distance is 46,000,000 and this gives the angular diameter of Sun Seen from Mercury at 1.73434325degrees. The Aphelion distance of Mercury is 69,820,000 and this gives the angular diameter of Sun as seen from Mercury at 1.14247784degrees, almost half a degree difference. You can compare this to earth and Sun.