Nothing quite says “independence” like striving to get away as far as possible, and today Earth achieved it as it reached its aphelion, its furthest distance from the Sun.
Today, Earth will be 152.1 million kilometers (94.51 million miles) from our star, having reached peak distance at 3am ET (6am UTC) this morning. This means it will be 1.67 percent farther than the average Earth-Sun distance, known as an astronomical unit or AU, which measures 149.6 million kilometers (92.96 million miles).
Every year the Earth’s perihelion (closest approach to the Sun) occurs in January and its aphelion happens in July. This year, it happens to fall on July 4, Independence Day in the USA. This doesn’t, however, mean that Earth will be at its coldest and you should stock up on cold medicine, despite what anyone spouting the “aphelion phenomenon” says.
Every year, proponents of the so-called aphelion phenomenon share posts about how between June and August our planet will experience unusually cold weather, which will have an impact on colds and flu, meaning everyone should wear warm clothes and take vitamins and supplements to boost their immunity. Quite aside from the overwhelming evidence that vitamins and supplements do very little for the average person, you’d think more people would have noticed that for a couple of months every year the Northern Hemisphere turns into scenes from The Day After Tomorrow.
If Earth's orbit of the Sun was perfectly circular, our distance to the Sun would be constant, but it's elliptical, so the distance varies throughout the year. However, the energy we get from the Sun does not differ much between helions because the distance at each only differs by about 2 percent– around 4.8 million kilometers (3 million miles) – from our planet's usual distance.
"Seasonal weather patterns are shaped primarily by the 23.5-degree tilt of our planet's spin axis, not by the mild eccentricity of Earth's orbit," explained Professor George Lebo for NASA back in 2001. This is why July is the Northern Hemisphere's hottest month, not its coldest, despite the distance.
The Northern Hemisphere has more large landmasses and fewer large bodies of water than the Southern Hemisphere, so it experiences hotter summers and colder winters. How? Because Earth is basically lopsided. During the Northern Hemisphere summer, the North Pole is tilted towards the Sun, meaning the Sun is shining almost straight down on more land, which heats up easily and raises the temperature of entire continents.
“Northern continents baked by the aphelion Sun elevate the average temperature of the entire globe. Six months later, in January, the situation is reversed as our planet presents its water-dominated hemisphere to the Sun,” NASA explained.
So no need to dig out your woolly jumpers, it's more likely you'll need the sunblock, especially if you're outside celebrating the fourth of July.