Temperatures reached record levels this week.
In the days following Independence Day, thermometers rose to abnormal levels in many parts of the world. With temperatures as high as these, it might come as a surprise to hear that on Thursday (July 6) at 4:06 PM EST (2006 GMT), our Earth will reach the point in its orbit where it is farthest from the Sun in space.
Called aphelion, the Sun will be at that moment 94,506,364 miles (152,093,250 km) from Earth (measured center-to-center), or 3,103,330 miles (4,994,325 km) farther than when Earth was closest to it (called perihelion). January 4, the difference in distance equals 3.29%, which makes a difference in the radiant heat received by the Earth of about 7%; Change only one part out of 30.
Related: How far is the earth from the sun?
In fact, it is not surprising that if you ask most people what month of the year they think the Earth is closest to the sun most likely they will say we are closest during June, July or August. But our warm weather isn’t about our distance from the sun. Because of the tilt of the earth’s axis by 23.5 degrees, the sun is above the horizon for different periods of time in different seasons. The tilt determines whether the sun’s rays hit us at a lower angle or more directly.
At the latitude of New York, the nearly direct rays at the summer solstice on June 21 generate three times as much heat as the oblique rays at the winter solstice on December 21. The heat received by any area depends on the length of daylight and the angle of the sun above the horizon, hence the marked differences in temperatures recorded in different parts of the world.
Climatic fallacy
When I attended Henry Bruckner Junior High School #101 in The Bronx, my earth science teacher, Mr. Saul Shenberg, told us that because we are farther from the sun in July and closer in December, that difference tends to warm the winter and cool the summer…at least in Northern Hemisphere.
This certainly sounds logical, however the fact of the matter is that the predominance of large land masses in the northern hemisphere works the other way and actually tends to make northern winters colder and summers hotter!
Interestingly, the times when the Earth is at its closest and farthest point from the sun roughly coincide with two important holidays here in the United States: We are closest to the sun on New Year’s Day and farthest from the sun on Independence Day.
For those living in Canada, Apogee roughly coincides with their national holiday — Canada Day — on July 1.
But in fact, depending on the year, the date of perihelion can vary from January 1st to 5th and the date of apogee can vary from July 2nd to July 6th.
Joe Rao is a teacher and guest lecturer in New York Hayden Planetarium. He writes about astronomy for Natural History Journalthe Farmers’ almanac and other publications.
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