July 4 Aphelion

It is July 4, and a commonly forgotten astronomical phenomena is occurring today; the aphelion. The aphelion is the day that the Earth is the farthest distance from the Sun during its orbit. Earth’s orbit is not a perfect circle, it is an ellipse. This means there is a point during orbit when the Earth is farthest and closest to the Sun.


The Earth is about 3.3% farther away from the Sun than when it is at is closest during the perihelion in January. It might not make sense that the Northern hemisphere is warmest when the Earth is farthest from the sun but the small decrease in solar radiation seen during the aphelion is negligible compared to the seasonal variations caused by the Earth’s tilt.

So while you are out celebrating Independence Day, don’t forget that we are the farthest from the Sun we will be all year.