Aphelion and Perihelion describes the furthest and closest distance the Earth is to the Sun, respectively. The Earth is farthest from the Sun (Aphelion) roughly two weeks after the June Solstice, and closest to the Sun (Perihelion) roughly 2 weeks after the December Solstice.
Earth’s Furthest Distance From the Sun
At the moment of aphelion, the Sun will be over 94 million miles away (measured center to center), or over 3 million miles farther as compared to when the Earth is closest to it (called perihelion). The actual number varies year over year.
If you ask most people which month of the year they think Earth is closest to the Sun, most would probably say during June, July, or August. But our warm weather doesn’t relate to our distance from the Sun. It’s because of the 23.5-degree tilt of the Earth’s axis that the Sun is above the horizon for different lengths of time at different seasons. The tilt determines whether the Sun’s rays strike us at a low angle or more directly.
At New York’s latitude, the more nearly-direct rays at the Summer Solstice of June 21st, bring about three times as much heat as the more slanting rays at the Winter Solstice on December 21. Heat received by any region is dependent upon the length of daylight and the angle of the Sun above the horizon. Hence the noticeable differences in temperatures that are registered over different parts of the world.
A Climatological Fallacy
When I attended Henry Bruckner Junior High School in The Bronx, my ninth grade earth science teacher, Mr. Shenberg, told all of us that because we were farthest from the Sun in the July and closest in January, that such a difference would tend to warm the winters and cool the summers—at least in the Northern Hemisphere.
And yet the truth of the matter is that the preponderance of large land masses in the Northern Hemisphere works the other way and actually tends to make the winters colder and the summers hotter.
Interestingly, the times when the Earth lies at its closest and farthest points from the Sun roughly coincide with two significant holidays: we’re closest to the Sun around New Year’s Day, and farthest from the Sun around Independence Day. Actually, depending on the year, the date of perihelion can vary from January 1 to 5; and the date of aphelion can vary from July 2 to July 6.
One misconception we often read in letters, emails, and comments from our readers is the idea that it’s cold in the winter time because the Earth is father from the Sun. While this assertion may sound good, it’s actually just the opposite. It may seem strange to learn that, while the U.S. and Canada are experiencing their coldest temperatures of the year, the Earth is actually closer to the Sun than at any other time during the year.
Earth’s Closest Distance to the Sun
Perihelion can fall anywhere between January 2 and January 6 in a given year. At that point in its orbit, the Earth is over 91 million from the Sun, a difference of about three million miles from its farthest point, or aphelion.
It’s All About The Tilt
Even though most of us learned in school that seasons are controlled by the tilt of the Earth’s axis, rather than by its distance from the Sun, many people forget. We experience summer or winter conditions based on whether our half of the Earth is pointed toward the Sun or away from it. While we’re battling ice and snow in the Northern Hemisphere, our neighbors to the south are enjoying summer, and vice versa.
A three million-mile change in relative distance may sound like a lot, but our overall distance from the Sun is so great that this otherwise large figure amounts to a drop in the vast astronomical bucket of infinite space. This slight change in distance has virtually no effect on our weather throughout the year.
So, while you’re shivering and scraping the ice off of your car’s windshield during the winter, try to remember that the Sun is actually three million miles closer than it was in July. Maybe that will help you feel a little warmer!