Earth farthest from sun

Earth farthest from sun

4^th July, 2014 – Aphelion day

We all know that earth goes round and round around the sun. Well it almost does that but there a small twist to the statement. It ALMOST goes in a circle. Thanks to Kepler, who gave us insight into how these wanderers go around the sun, all planets in our solar system travel around the Sun in elliptical orbits. It's Kepler's 1st Law. Some planets go around sun in more elliptical orbit than others. Most planets follow orbits that are more elliptical than Earth's orbit. So in a sense earth’s orbit is closest to being a circle in the whole solar family. Even then the slight deviation from a circle gives us two positions of earth when it’s farthest and closest to sun.

The orbits of Mercury (red), Earth (blue) and Mars (black). The solid lines indicate each planet's elliptical path around the Sun. The dotted lines show circular paths with the same mean separation from the center. Earth is almost exactly the same distance from the Sun at aphelion and perihelion, but the orbits of Mars and Mercury depart significantly from a circle.

On July 4th, 2014 at 15 hrs UT or at 20:30 IST, the Earth is at its farthest point from the Sun (aphelion), the distance at that time is 152,097,040 km, which is about 5 million km further away than its closest point in early January. It does appear strange that in July we have earth farthest away from sun. Isn’t it? And to top it all total energy received from sun by the globe on aphelion is around 7% less than what we receive when it is closest to the sun (perihelion).

Now you may ask if sun is farthest then why is the temperature not going down?  There are many reasons to it. Blame it on the tilt of earth’s axis. Actually, our seasons are determined by the tilt of the Earth and not by how close the Earth is to the Sun. Well that’s another story to tell.

Sunlight raises the temperature of continents more than it does oceans. (Land has a lower heat capacity than water) In July (aphelion) the land-crowded northern half of our planet is tilted toward the Sun. Aphelion sunlight is around 7% less than sunlight at perihelion, but it nevertheless does a good job warming the continents. In fact, say climate scientists, northern summer in July when the Sun is more distant than usual is a bit warmer than its southern counterpart in January.

So enjoy the warm or rather scorching sun (or cloudy day!) on 4^th July as a celebration to the Aphelion day.