At 12:46pm EDT on Friday, some 94,507,803 miles yawned between the Earth and the sun. Known as Aphelion Day, today marks the largest distance between the two bodies this year, which is over 1.5 million miles farther than the average span.
And yet, the heat wave hit particularly hard today, prompting record-breaking temperatures around the southwest and exacerbating brush fires. All-time highs have registered across the globe, as well, including Russia and Canada, where 33 individuals died of the scorching weather in Montreal.
But, if our planet is as far away from the sun as it can be, why is it still so hot outside?
Science, as broken down by Gizmodo, harbors the answers.
The Earth circles around the sun in an ellipse and at a tilt of a 23.5-degree angle. Hence, during June, the planet’s northern section lists toward the sun, while, during January, its southern half points closer to the star. Sun rays reach the Earth’s surface quite evenly during March and September, however.
Think about the reversal of summer and winter in the northern and southern hemispheres – this explains it. Well, this also cues to why it is hot during the summer – the Earth receives more light, which translates into more energy, which generates more heat.
Yet, according to an old NASA document cited by Gizmodo, our globe gets around seven percent less sunlight on Aphelion Day. Nonetheless, the northern half of the Earth comprises more landmass than the southern – thus, it heats up faster and remains hot longer.
There is another interesting fact that adds to the sizzling weather. Washington Post‘s Greg Porter points out to an expansive stretch of high pressure in the atmosphere above the eastern U.S., which pushes air down. As it sinks and compresses, air hikes up its temperature, causing what is sometimes dubbed “heat domes.” Further exacerbating this phenomenon is its stubbornness to dissipate once developed.
“Not only is the current upper-level high going to stick around, but also it’s going to become stronger and larger over the next several days,” Porter wrote on July 3. “Over the weekend, the same ridge of high pressure that has been dominating the weather over the East will expand west.”
Could global warming play a role too? Perhaps. The last three years have seen unusually intense weather events – from hurricanes to heat waves. But any substantial shifts in the Earth’s climate ought to manifest themselves over the long-term, which we are yet to experience.
Many factors have aligned to make today a special occasion for space and science buffs, so Happy Aphelion Day!